The script for the Photoshop Advanced Workshop is intended exclusively for use in class at the University of Applied Arts Vienna and should serve as a reference work for all course participants. It may not be passed on to third parties.

Color modification

Modifying certain colors in an image is one of the most common image processing tasks. Different starting positions and different color targets require different approaches.

Let’s look at the most important possibilities one by one. We will not dwell too long on the areas where we have already gained experience. It will be important for us to highlight the advantages and disadvantages of the various techniques.

> Open exercise file 7.

Editing colors

When you talk about color modification, it’s not always about coloring. Often you just want to push existing color tones in a certain direction. In such cases, I like to reach for the Camera Raw filter.

Camera Raw filter:

All the tools and settings we learned about in Raw Conversion are also directly accessible in Photoshop as Camera Raw filter.

Since we want to work non-destructively as always, we first convert a duplicate of the background layer into a Smart Object.

> Duplicate background layer, Smart Object.

Since we are only going to work on the red tones of the car body and don’t want to bother with selection creation, we will activate the corresponding selection that I have deposited for you as an alpha channel.

> Switch to Channels. Cmd-click channel bar “Rote Karosserieteile”.

> Switch back to the Layers palette.

> Filter / Open Camera Raw Filter.

The Camera Raw filter is applied to the Smart Object as a Smart Filter and can thus be modified or readjusted at any time and completely without loss.

Let’s immediately bring up the Color Mixer. Here you can make color modifications according to the HSL scheme.

> Hue: Set red tones to magenta -100.

> Saturation: Red tones +50, magenta tones +25.

> Luminance: Red tones +50, magenta tones +50.

The HSL scheme of the Color Mixer allows to influence the three aspects that characterize a pixel separately. However, true colorization is only possible to a limited extent with Camera Raw’s Color Mixer. Replacing a color with any other color is not always possible this way.

Replace Color

If we want to achieve a strong recoloring, we first have two options: the Color Replacement Tool and the Replace Color dialog.

Both options cannot be applied to a Smart Object. If you want to work non-destructively, you have to make do with an ordinary layer duplicate. 

Let’s try our luck with the Replace Color dialog.

Replace Color dialog:

The dialog offers a combination of the two well-known dialogs Color Range and Hue/Saturation.

> Hide Color Mixer layer.

> Duplicate background layer.

> Switch to Channels. Cmd-click channel bar “Rote Karosserieteile”.

> Switch back to Layers palette, create layer mask, activate layer thumbnail.

> Image / Adjustments / Replace Color.

We start by defining the colors to be changed.

> Activate Localized Color Clusters.

> Set the Fuzziness slider to 100.

> Click into middle red.

> Add all red tones while holding down the Shift key.

We add tones of the original color to our selection until a large part of the body is selected. Only then do we define the new color.

> Open the color picker for result color: 100-30-100-30.

Finally, we fine-tune the color assignment. We modify the fuzziness until the transitions between the modified color tones appear smooth.

> Refine the result with the Fuzziness slider.

The procedure has its limitations. In fact, the Replace Color dialog is not intended for recoloring entire areas. Its use is most useful when you need to capture specific color ranges in order to apply a new color to them.

• A disadvantage of the Replace Color dialog is that we cannot work with a Smart Object, i.e. our measure cannot be readjusted at a later time.
• One advantage is that we can target a very specific color tone for coloring.

Coloring

If we want to get the maximum out of coloring, the first thing to do is to use Hue/Saturation. We already learned how the dialog works in the Basics workshop. Now let’s take a closer look at it.

Hue/Saturation:

> Hide Replace Color layer.

> Activate background layer.

> Load car body layer mask as selection.

> Adjustment layer: Hue/Saturation.

> Open the Color Range menu.

We could now select the Red Tones entry of the Color Range menu. This would give us a concrete preselection for coloring. However, we want to take a more differentiated approach.

Classic coloring starts from zero, i.e. a color tone with a certain saturation is added to the pure brightness values of the image. Think of colorizing so-called black and white photos, as it was done in times before the invention of color photography with brush and paint.

If you want to colorize in Photoshop in the classic way, activate the Colorize checkbox.

However, it is much more precise to define the color range to be changed manually. So we will not activate the Colorize checkbox and instead use the On-image adjustment tool.

> Activate the On-image adjustment tool.

> Edit saturation: click into the red of the body, drag.

> Edit hue: Cmd-click into the red of the body, drag.

> Reset.

> Click in middle red to the right of the louvers.

Now, before we move a slider, let’s take a look at the other elements of the Properties palette. Two major changes have occurred there.

1. Photoshop has automatically set the color range to reds and …
2. Several small adjustment sliders have appeared between the (upper) input color bar and the (lower) output color bar.

With these small sliders we can determine the color range we want to change very precisely. But first, let’s assign a different hue so we can judge the effect.

> Hue +110.

You can clearly see that we have by far not yet captured all the possible red tones in the body. We now want to improve this.

• With the two inner sliders we can restrict or expand the color range.
• The two outer sliders can be used to soften the color transitions. So the two outer sliders do the same thing as the Fuzziness slider of the Replace Color dialog.

First we want to define the color range more precisely. So let’s set the two Fuzziness sliders to zero, so to speak.

> Move the Fuzziness sliders as close as possible to the color range sliders.

> Click in the field between the two Color Range sliders and move the sliders until as many parts of the car body as possible have been recolored.

We have now found the exact center of the color range that we want to change. Now we need to add more shades to the color range. We want to extend the color range to the left and right.

By moving the two Color Range sliders, we gradually bring the neighboring color ranges into the image.

> Drag the left Color Range slider to the left to 235°.

> Drag the right Color Range slider to the right to 40°.

We pull just enough on the sliders until we can no longer achieve any improvement. To go further would be pointless.

Now we have to improve the transitions between the different color gradations of the selected color range. And we achieve this by widening the respective transition range with the help of the two tolerance sliders.

> Drag the left Fuzziness slider to the left to 200°. 

> Drag the right Fuzziness slider to the right to 60°.

Here, too, we do no more than is just necessary.

If we didn’t get all the tones, we can add more red tones to the coloring. For convenience, we will do this in a new adjustment layer.

> Load body layer mask as selection.

> Adjustment layer: Hue/Saturation.

> Click with the On-image adjustment tool into the reflection of the front fender.

> Hue +110.

> Drag left Color Range slider to the left to 200°.

> Drag right Color Range slider to the right to 30°.

> Drag left Fuzziness slider to the left to 180°. 

> Drag right Fuzziness slider to the right to 90°.

The great advantage of this method is that the color areas to be changed can be captured very precisely and the appearance of false colors can be avoided. In most cases, colorizing with the help of a Hue/Saturation adjustment layer according to the shown procedure leads to a perfect result.

Extreme recoloring

As long as the brightness of the source color and the target color are not too different, recoloring in this way is easy. To target extreme colors, such as black or white, or to recolor a very dark color into a very light color, is usually not so easy. The problem is that extreme color changes require extreme intervention in tonal values. In such cases, before the desired color tone has even been achieved, the tones of the image has often already gone.

There are different ways to achieve an acceptable result with extreme recoloring.

• In some cases it is sufficient to adjust the tone values in advance with the help of a Curves adjustment layer.
• Sometimes it helps to apply the color modification to the highlights, the shadows and the midtones in different intensities. For this you could use appropriate luminance masks or as just shown multiple Hue/Saturation adjustment layers.
• Sometimes playing around in the Channel Mixer leads to success.
• The application of the Match Color dialog also sometimes provides useful results.

The first of the above-mentioned options works only for moderate cases. The latter two methods usually involve a great deal of effort and often result in nerve-wracking trial-and-error actions.

Another way to deal with difficult cases leads us once again to the Camera Raw filter, the possibilities of which we have not yet fully learned with regard to recoloring.

Let’s activate again the area selection of the red car body parts.

> Load body layer mask as selection.

> Duplicate background layer, Smart Object.

> Open Camera Raw filter and bring Basic Panel to view.

In Camera Raw we find an even more basic way to change colors than with the Color Mixer. We can modify the temperature and tint in the Basic Panel using the Lab scheme.

We make use of the Lab scheme to adjust the colors separately from the tones. In a first step, we want to adjust the temperature, tint, and brightness for this so that the target hue is easy to achieve in a second step. What sounds a little cryptic at first will become clear immediately. We want to turn the red of the body into a bright yellow.

> Temperature +100.

To get closer to this, we also need to modify the tint heavily.

> Tint +80.

This obviously doesn’t do the job. But we are already moving in the right direction.

Now we lighten tonal values. We do this by changing the various tone setting options from Exposure to Blacks.

> Exposure +0.30, Contrast +30, Shadows +30.

This gives us a good starting color for the shift to yellow. And we now do this as usual in the HSL scheme of the Color Mixer.

> Open the Color Mixer panel.

> Hue: Red tones +100, orange tones +100.

> Saturation: no change, because the desired saturation level has already been reached.

> Luminance: red tones +50.

I think we have achieved quite a good yellow tone. What is still disturbing is the clear noise that can be seen in the previously dark areas. Of course, we’ll tackle this with the adjustment options of the Detail panel.

> Open the Detail panel.

> Noise Reduction 100.

> Detail 50.

> Contrast 0.

> Color Noise Reduction 50.

We reduce the noise, but take care not to destroy the textures and the reflections.

Finally we increase the contrast a bit in the gradation curves.

> Curves minimal contrast increase and OK.

This looks quite acceptable. Of course, we would have had to spend a little longer on it to get a perfect result. But it turns out that Camera Raw offers very effective ways to do extreme recoloring.

Let’s go one better and color the body white. A color goal that is sometimes very difficult to achieve.

> Duplicate Camera Raw layer, hide lower Camera Raw layer.

> Open Camera Raw filter again.

> Show Color Mixer.

> Hue: no change, since the desired color setting has already been achieved.

> Saturation: red tones -100, orange tones -100.

> Luminance: red tones +100, yellow tones +100 and OK.

Black can also be achieved relatively comfortably in this way.

With the two high-end tools Hue/Saturation and Camera Raw, we can overcome all the challenges that coloring poses to us. But alternative techniques such as Replace Color also have their place.

So far, we have been concerned with creating quasi-natural color settings. The use and relevance of color effects has become widespread, not least due to the possibilities for changing colors in various apps on the smartphone.

Color Effects

Photoshop is of course the mother of all color effects. Because the topic is also increasingly important in the professional field, we will look at a few ways to create color effects in Photoshop.

> Open exercise file 8.

Black & White

Black and white conversions are quite popular and can be created quickly with the Black & White dialog. As we know, the process does not involve a mode change, but simply converts hues to tones. In other words: hue and saturation are removed, what remains is the luminance.

> Create adjustment layer Black & White.

The default conversion provides a normalized grayscale image.

For the conversion of color tones into gray values, black & white offers a huge scope. We can use one of the available presets to change the character of the image.

> Try out various presets.

> Create a sepia effect: Activate Tint and assign a color tone.

Since we have already dealt with this in the Basics workshop, I would like to abbreviate the discussion of Black & White and just point out a technique that allows a more differentiated implementation.

> Reset dialog.

> Activate the On-image adjustment tool and drag it over the image.

Working with the On-image adjustment tool is quite intuitive. The tonal values you want to lighten or darken can be quickly modified by moving the cursor left or right in the image.

• If you hold down the Option key while dragging, the change is made in smaller steps.
• If you hold down the Shift key while dragging, the change is made in larger steps.

> Option-drag and Shift-drag.

The layer mask of the adjustment layer can be used to restrict the Black & White conversion to certain areas of the image.

> Activate adjustment layer layer mask.

> Activate Gradient Tool, Radial Gradient, Black/White.

> Mask image center circularly.

> Finally, hide the Black & White adjustment layer.

Photo Filter

Even more popular than black & white conversion are photo filter effects.

> Create adjustment layer Photo Filter.

Here you can use one of the classic photo filters from the Presets menu and/or define a color tone and density yourself.

You want to achieve two main goals by using a photo filter:

1. One is to simulate classic photo filters or film emulsions to create a certain vintage effect.
2. On the other hand, the aim is to provide images with a certain mood, i.e. to visually emotionalize them.

The Preserve Luminosity checkbox plays an important role. It ensures that only the colors and saturations are captured by the settings, but not the tonal values.

> Deactivate the Preserve Luminosity checkbox and activate it again.

> Warming Filter 85, Density 50%.

If you want to push the color effect or offset it against the existing colors in the image, set a blending mode for the adjustment layer.

> Adjustment layer Blending Mode: Overlay.

If you want to apply the color effect in a differentiated way, e.g. only in the shadows and darker mid-tones, but leave out the highlights, you define a tonal range for the adjustment layer.

> Double-click on the adjustment layer bar.

> Blending Options: Underlying Layer 0/120…170 (divide the white slider using the Option key) and OK.

This gently reduces the effect in the highlights of the image.

There are no limits to experimentation here. Don’t get too hung up on numbers when working with color effects. When creating a look, it’s all about the visual impression.

> Open exercise file 9.

Effects via Camera Raw filter

Camera Raw gives us a wealth of options for creating black and white and color effects.

> Duplicate background layer, Smart Object.

> Filter / Camera Raw Filter.

Since we’ve already had a good look at Camera Raw, let’s take a quick look.

> Edit: Activate B&W.

> Drag various Basic sliders and finally Option-Reset Basic.

We can use all the sliders of the Basic settings to adjust the tonal values of the black and white conversion. Of course also the Curves of the composite channel and the HSL settings of the B&W Mixer.

> Curves: slight contrast increase.

> B&W Mixer / Hue: Reds -50, Oranges -50, Yellows +15.

> Reset all changes via Option-Reset of the Camera Raw dialog.

We can create a photo filter effect or look using the numerous presets that Camera Raw offers.

> Press the Presets button, open the Creative menu: Activate Vintage Instant.

> Reset the look via Option Reset of the Camera Raw dialog.

And push or pull back color ranges locally.

Crop:

> Switch to Basic and activate Masking.

> Create New Mask via Subject (Shoes).

> Completely crop shoes with Brush: Subtract-Brush (Size 2, Feature 10, Flow 100, Density 100), Add-Brush via Option-Button (Size 2, Feature 10, Flow 100, Density 100).

> Disable Show overlay.

Colorize:

> Color bar: Hue -50, Saturation 0.

> Cancel Camera Raw.

Now let’s take a quick look at two very special features for color modification – the Channel Mixer and the Match Color option.

Channel Mixer

The Channel Mixer allows you to mix the color information of the color channels. Working with the Channel Mixer takes some getting used to. In CMYK, the procedure follows the logic of four-color printing, so it should essentially not be a problem. Thinking in the RGB scheme, on the other hand, is difficult.

> Create adjustment layer Channel Mixer.

The great advantage of the channel mixer is that, if you proceed carefully, the color information of all color channels is used completely and no tonal values are lost overall.

Here are the two basic principles that should be considered when working with the Channel Mixer.

1. By dragging the sliders, the respective color components in a specific output channel can be changed. You can also think of it this way: Tonal values are moved from one channel to another.
2. If you do not want to overstrain the color and tonal balance, the total value in each of the output channels should not exceed 100%.

Increase saturation with the Channel Mixer:

The Channel Mixer is also very useful for increasing the saturation in an image. And this process is easier to understand than a color correction.

Increasing the saturation means increasing the color intensity. Therefore, in each of the Output Channels, we set the portion of the corresponding source channel to the maximum and reduce the other two color portions according to the second basic principle.

> Output Channel Red: Red +200%, Green -50%, Blue -50%.

> Output Channel Green: Red -50%, Green +200%, Blue -50%.

> Output Channel Blue: Red -50%, Green -50%, Blue +200%.

Finally, to reduce the effect a bit, we reduce the layer opacity to 50%.

> Layer Opacity 50%.

For sure, the Channel Mixer is not an easy tool to use. But in certain cases it is worth a try.

> Open exercise files 10a and 10b.

Match Color

Match Color allows you to transfer the colors of one image to another.

> Duplicate background layer of Bsp10a. (Smart Object not available).

> Image / Adjustments / Match Color.

> Image Statistics, Source: Bsp10b and OK.

> Hide Layer.

If selection areas are defined in source and/or target image, the color transfer is based on the colors of the selected area. This way, colors within the current image can also be used for a transfer.

> Select the man’s face and press cmd+J.

> Create duplicate background layer.

> Image / Adjustments / Match Color.

> Source: Bsp10a, so select the image itself as source.

> Layer: Select Layer 1 (face of the man) and OK.

Let’s leave it at this point and finish the topic of color modification and coloring.

> Open exercise file 11.

Detail retouching

One of the main tasks in image processing is retouching in the broadest sense. I dare to say that there is no image that does not need some retouching.

We distinguish detail retouching from area retouching. First, let’s take a quick look at the most important tools for detail retouching. You should be familiar with the Clone Stamp Tool, the Healing Brush and the Patch Tool. So I’d like to focus our attention here on a few perhaps less familiar aspects.

Clone Stamp Tool

The most prominent detail retouching tool is, of course, the Clone Stamp Tool. We can improve its handling with a trick or two.

Obviously, we will stamp the retouch result into a new, empty layer. Never should the retouching affect the subject itself. So we create a new, empty layer and make sure that All Layers is selected in the Sample menu of the options bar.

> New empty layer, labelled “Stamp”.

> Activate Clone Stamp Tool, round soft tip, 50 px, 0% hardness, 100% opacity, Sample: All Layers.

> Remove a few moles.

Since in most cases we want to clone parts of the image with the Clone Stamp Tool, i.e. transpose them unchanged, we ignore the options for Blending Mode, Opacity, Flow etc. in the options bar.

However, the Aligned and Sample options are important, as is the Ignore Adjustment Layers button. Let’s look at the effects of the latter.

> Create adjustment layer Curves, brighten image.

> Switch to the underlying retouch layer.

> Remove a few moles with the Clone Stamp Tool.

The retouching result includes the correction of the adjustment layer as expected. Accordingly, the retouching turns out too bright.

> Activate the Ignore Adjustment Layers button.

> Remove a few moles with the Clone Stamp Tool.

The correction of the adjustment layer is ignored. The retouching result is perfect.

Two more buttons in the options bar are also practical:

• The left button opens the Brush Settings palette.
• The right button opens the Clone Source palette.

In the Clone Source palette, up to five different copy sources can be defined. This can be helpful for very repetitive tasks. If the same, few copy sources have to be accessed again and again, this saves the repeated, manual definition of the copy source.

While this option is rarely used with the classic Clone Stamp tool, it can be useful when working with the Healing Brush.

Healing Brush and Clone Source palette

> New, empty layer “Healing Brush”. 

> Activate Healing Brush, 50 Px, 0% Hardness, 100% Opacity, Source: Sampled, disable Aligned, Sample: All Layers, Ignore Adjustment Layers, Diffusion 5.

> Clone Source 1: capture from ideal skin texture from blurred area of left shoulder and apply multiple times.

> Clone source 2: take an ideal skin structure from the sharp area of the right shoulder and apply it several times.

> Alternate application of the two clone sources.

Overlay view:

A little help when working with different clone sources is provided by the overlay view. What is irritating and counterproductive in classic stamping sometimes makes sense when using several different clone sources.

> Activate Show Overlay, activate Clipped (restricts the overlay view to the current brush size), activate Auto Hide.

> Apply Healing Brush.

The overlay shows if I have chosen the right clone source. If not, I have to go to another saved clone source or even specify a new clone source.

The auto-hide feature makes it easier to work with in that the overlay is hidden during application.

> Disable Show Overlay.

Clone Modification:

The Clone Source palette also provides the ability to modify the clone. To achieve a more inconspicuous retouching result, the clone can be flipped, scaled and rotated.

> Activate Flip horizontal button, Scale 120%, Rotate 25° and apply.

> Finally, reset the modifications via palette menu Reset Transform and deactivate Show Overlay.

Diffusion level:

We haven’t yet discussed a small but subtle adjustment option in the options bar: Diffusion.

With the diffusion value you determine how fast the retouching result adapts to the environment. If you want to preserve the finest microstructures during retouching, choose a rather low diffusion value. For very soft environments, you can choose a higher diffusion value.

In our case, a diffusion level of 5 is just right for all skin areas.

Patch Tool

Somewhat larger areas to be retouched can be worked on much better with the Patch Tool than with the Healing Brush.

Since the Patch Tool always needs to access a real pixel source, for a non-destructive approach we don’t create a new, empty layer, but work into a copy of the background layer.

> Duplicate background layer, Hide all layers above it.

> Activate Patch Tool, Mode Normal, Activate Source, Diffusion 5.

> Select scar generously and move the selection to the lower right.

> Undo retouch cmd+Z.

> Set diffusion level to 1.

> Repeat retouching.

If the diffusion degree is too low, the processing leaves clear traces. With the relatively diffuse pore structure, a higher diffusion value is recommended.

> Set the diffusion level back to 5.

> Repeat retouching.

If you want to limit the view of the Patch Tool to the retouched zones, create a corresponding layer mask.

> Create a layer mask based on the current selection.

Even very large zones can sometimes be repaired satisfactorily with the Patch Tool.

> Duplicate background layer, Hide all layers above it.

> Activate Patch Tool, Mode Normal, Activate Source, Diffusion 5.

> Select tattoo generously and move the selection to the lower right.

> Create layer mask based on the selection.

> Correct one or the other detail with the Healing Brush in a new, empty layer.

But the Patch Tool can be used in another way, if we switch to content-based touching up.

> Hide all layers except the background layer.

> New empty layer “Content-Aware”, Structure 7, Color 10, Sample All Layers.

> Select scar generously and move the selection to the lower right. 

The advantage of using this way is that we don’t have to duplicate the background layer, but can work into an empty layer just as we do with the Clone Stamp Tool and the Healing Brush. In our case, Content-Aware does not provide a usable result. The option is only suitable for applications where texture has to be created artificially.

Spot Healing Brush

The Spot Healing Brush is the local counterpart to the content-based touch-up. Since, unlike the Clone Stamp Tool and the Healing Brush, no dedicated source location can be determined, the application cannot really be controlled well.

> Activate Spot Healing Brush, Type Content-Aware, Sample All Layers.

> Create a new, empty layer.

> Retouch the scar.

However, in simple cases like this, the tool sometimes works quite well.

You see, the known retouching tools are partly redundant. In which case you use which tool is a matter of experience. If you can’t achieve the desired result with one tool, try another.

The retouching tools can be refined with numerous settings. Whether and to what extent you use these options must be weighed up on a case-by-case basis. In any case, the goal is to achieve a useful retouching result with the least possible effort.

Content-Aware Move Tool

If you want to move local image content, using the Content-Aware Move Tool is recommend.

> Activate Content-Aware Move Tool, Mode Move, Structure 1, Color 10, Sample All Layers, Transform On Drop.

> Hide all layers except the background layer.

> Create a new, empty layer.

> Select scar generously and move the selection to the lower right, OK.

Here two things happen at the same time: 

1. The image content is moved to a different position in the image.
2. The original position of the image content is retouched based on its surroundings.

This may not always be as successful as in our example, but it does sometimes produce quite useful results.

If you don’t want to move a local image content, but just extend it, you sometimes get better results if you select Extend as application mode.

> Activate Content-Aware Move Tool, Mode Extend, Structure 1, Color 10, Sample All Layers, Transform On Drop.

> Hide all layers except the background layer.

> Create a new, empty layer.

> Select the upper nail of the tattoo and move it vertically upwards, OK.

And with this we already switch over to the category of area retouching.

Area retouch

> Open exercise file 12.

If you want to remove large elements, you will not use the tools for detail retouching. Good results can be achieved in such cases with Content-Aware Fill.

Content-Aware Fill

> Select Lamb and Sheep with Lasso.

A classic touch-up is out of the question here. The area to be retouched is by far larger than the places that can be used to create a patch. In such cases, the Content-Aware Fill dialog is used.

> Open Edit / Content-Aware Fill.

Content-Aware Fill has come a long way. The algorithms and the results are now quite usable and working in the dialog is easy and intuitive.

The green signal color marks the sampling area. This is the area of the image from which image information is taken for filling.

The area retouching already looks quite good in the preview, but it can still be improved. To do this, we exclude the hedge areas from the sampling with the Minus Brush.

> Activate Sampling Brush Tool, Subtract, Size 150 Px and remove the hedge areas.

> Output Settings: New Layer and OK.

> Deselect.

The content-based fill basically turned out quite well. Only the border areas should be reworked a bit.

> New empty layer.

> Healing Brush 200 Px, Mode Normal, Sample All Layers.

> Retouch the border areas of the fill.

> Open exercise file 5.

Tonal correction

Once the retouching is finished, the next step is to check the tonal values and subsequently to correct them. Tonal correction, as we know, is usually done before color correction.

We have already heard a little about advanced tonal correction in the discussion of luminance masks. Now it’s time to deepen our knowledge.

Standard tools for creating a tonal value correction are the Levels and of course the Curves. Both adjustment layers do more or less the same thing. They are just different to use.

Since the settings of the classic Levels are only linear, I usually go straight to the Curves, which are smoother to use.

Let’s take a quick look at the difference.

Curves

Linear contrast increase with the sliders:

> Create adjustment layer Curves.

> Drag the Black slider to the right: 15/0.

> Drag the White slider to the left: 240/255.

Increasing the contrast, as we have done here, turns out to be a bit crude. Simply moving the black point and the white point is called a linear contrast increase. This is exactly what Levels do when we spread the tonal values there, i.e. adjust the Input Levels accordingly.

Linear contrast enhancement with the eyedroppers:

We can also do this with the White eyedropper and the Black eyedropper, taking advantage of a hidden preview option.

> Reset Curves.

> Activate the Black eyedropper and, while holding down the Option key, click on the black slider and drag it to the right.

The darkest pixels of the image show up first in the white area. We darken these pixels to the deepest black by clicking with the Black eyedropper.

> Black eyedropper click on the darkest pixels.

Finding and setting the white point is done analogously.

> Activate White eyedropper and click on the White slider while holding down the Option key.

> White eyedropper click on the lightest pixels.

The key thing when working with the two eyedroppers is to hit the respective pixels accurately.

We see the correction has actually been made in the color channels.

If we want to make sure that a tonal value correction performed using an adjustment layer such as Curves only leads to a change in the tone values, while the color values remain unchanged, we set the blending mode of the adjustment layer from Normal to Luminosity.

> Blending mode adjustment layer Curves: Luminosity.

Contrast increase with an S-curve:

The advantage of Curves over a linear tonal correction in Levels is that we can start the contrast increase slowly and let it end slowly by creating a smooth S-curve.

> Reset Curves.

> Create S-Curve by setting two points: 50/40 and 205/215.

> Blending mode adjustment layer Curves: Luminosity.

I would like to give two small hints about the displays in the Curves palette.

Exact Histogram:

To the left of the histogram is a small warning icon. This indicates that the histogram shown is only an approximation of the tonal distribution. Clicking on the warning symbol forces Photoshop to calculate an exact histogram. An exact histogram is essential for accurate work.

> Click on the warning symbol.

Info Pigment/Ink vs. Light:

Let’s take another quick look at the Palettes menu and there at Curves Display Options.

Image editors working exclusively for print prefer the display of the tone value levels as a percentage of the print color. The preferred display mode can be quickly set here.

> Click on Pigment/Ink and again on Light and cancel.

Shadows/Highlights

You should already be familiar with the Shadows/Highlights dialog.

Since Shadows/Highlights is not available as an adjustment layer, but we still want to work non-destructively, we create a duplicate of the background layer and convert it into a Smart Object.

> Duplicate background layer, Smart Object.

> Open Image / Adjustments / Shadows/Highlights.

If the additional options are not yet shown, we activate the corresponding checkbox and take a closer look at the complete dialog.

> Activate Show More Options.

What exactly can be achieved with Shadows/Highlights?

Shadows/Highlights, as the name suggests, targets the shadows and highlights of the image. The midtones, on the other hand, are largely left out of a correction. This is always advantageous when parts of the image appear overexposed or underexposed. For example, the underexposed subject appears in front of the correctly exposed background or vice versa.

The dialog opens with a default setting that is useful for many of these cases. Of course, fine tuning must be done optically and manually.

Amount:

With the Amount sliders, one virtually makes an exposure correction for the respective tonal range.

• You lighten the shadows to make the details in the shadow areas visible.
• The highlights are darkened to make the details visible in the overexposed areas.

> Move the Amount sliders for Shadows and Highlights.

The prerequisite for a successful correction is, of course, that there is still something like details in the underexposed and overexposed areas. And that’s where it usually fails. Our 8-bit/channel image simply no longer contains the required image information in these extreme tonal value ranges.

To get everything out of the highlights and the shadows, these corrections would have to be applied earlier, in the course of the Raw conversion. Because in a 16-bit image, we can still get the most out of the tonal values.

But even then, if you don’t have a Raw file to fall back on, reaching for the Shadows/Highlights dialog is sometimes worth a try to strengthen the details in the darkest and the brightest zones of the image.

Tone:

Use the Tone slider to determine the range of tones to be corrected. For example, if you want to deal only with the darkest of the dark tonal values, select a low value for the tone width. If, on the other hand, you want to extend the correction to the mid-tone range, select a higher value.

> Move the Tone slider for Shadows.

Radius:

The Radius slider determines how far the correction extends from the specified tonal range into adjacent areas.

> Move the Radius slider for Shadows.

> Reset everything via Option Reset.

Currently, a correction is applied only in the shadows. So let’s concentrate on the shadows.

We want to lighten the shadows a bit, but keep the effect on the midtones small.

> Shadows: Amount 50, Tone 30, Radius 30.

> Disable Before/After via Preview checkbox and enable again.

As we can see, even in 8-bit/channel images there are still treasures to be found in the extreme tonal value ranges.

If we now want to strengthen the colors in the corrected zones, we can pull the Color slider.

> Color +60.

Mostly, however, I refrain from setting this very rough measure here. This is better done with a specific color correction, e.g. with the help of the Curves.

The Midtone slider is used to increase the contrast in the midtones and works like the Gamma slider in the Levels. I usually leave this slider untouched in the Shadows/Highlights dialog.

If you want to crop the highlights and the shadows, you do that in the Shadows/Highlights dialog by adjusting the clipping values for black and white. Again, I never make this adjustment in Shadows/Highlights. We do that much more accurately by dragging the White and Black sliders, such as in the Curves.

Since I can achieve all these options for correcting the tonal values in the shadows and highlights by other means, I only use the Shadows/Highlights dialog when I can expect a quick correction, i.e. where an exposure problem in said zones is obvious.

Exposure

The use of the adjustment layer Exposure also comes too late in an 8 bit/channel image for the reasons mentioned above. In fact, the possibilities of this function unfold fully only in HDR images, i.e. in images with 32 bit/channel bit depth.

Dealing with HDR (High Dynamic Range) would take us too far here. Aspiring professional photographers should deal with the issue, however.

If possible, we should carry out an exposure correction already in the course of the Raw conversion. As is well known, there is only limited room for this in an 8-bit image.

> Create adjustment layer Exposure.

> Drag the sliders.

• Dragging the Exposure slider adjusts the highlights and upper midtones. The extreme shadows are preserved longer.
• Drag the Offset slider to adjust the shadows and lower midtones. The extreme highlights are preserved longer.
• Gamma correction intervenes in the midtones. We already know this from other dialogs. The gamma slider is set to 1.00 by default.

Personally, I prefer to do an exposure correction, if it could not already be done in the Raw conversion, in Camera Raw anyway. So I don’t use an Exposure adjustment layer for 8-bit images.

> Hide Exposure adjustment layer. 

> Duplicate background layer, Smart Object.

> Open Filter / Camera Raw filter, bring Basic panel to view.

> Exposure +0,25, Shadows +20, Blacks -40 and OK.

Here we find many more possibilities to modify the exposure and the tonal values in an exact and differentiated way.

Since we have already dealt with Camera Raw enough, we will not pursue this any further.

> Open exercise file 13.

Color correction

Color correction is traditionally and sensibly done after tonal correction. Sometimes color casts that need to be retouched only become clearly visible after a change in brightness or after an increase in contrast.

So let’s start with a moderate contrast enhancement.

In order to better control color shifts during the entire process, however, we do not want to proceed at random, but rather use three tools that allow us to work precisely: the Info Palette, the Histograms and the Color Sampler Tool.

Info palette

> Show Info Palette.

Back in the Basics Workshop, I touted the Info Palette as a useful feature.

• The first panel of the palette should always show the values of the current color system. Here you can read what is going on.
• In the second panel, I usually have the Total Ink value displayed. The Total Ink value is the sum of the percentages of the inks cyan, magenta, yellow, and black.

As we’ve already heard, different printing processes allow different maximum total ink coverage. As a reminder, in sheet-fed offset printing with a 60 screen, the value for total ink coverage should not exceed 350%. Otherwise, too much ink would be applied in the darkest of the dark zones of the image and the screen would “close up”. If the halftone dots flow into each other, an undesirable shine will appear in the shadows of the printed image.

Let’s check the darkest parts of the image and see what we can expect in terms of total ink coverage.

> Use the cursor to check the shadows.

Nowhere in the image can we detect a value higher than about 320%. So we are absolutely in the safe area as far as the total color coverage is concerned.

Since we can be reassured on this point for the time being, and subsequently want to make a color correction whose result works well in print, we temporarily switch the display of the second panel to Proof Color.

> Set the display of the second panel to Proof Color.

Proof Color of course shows the CMYK values with the color profile applied.

Which color profile is embedded in our image? Currently Adobe RGB (1998). The CMYK values displayed refer, of course, to our CMYK working color space Coated FOGRA39.

To be informed at any time about the color profile effective in the image, I have it displayed in the Info palette.

> Open the Info palette menu and Panel Options.

> Status Information: Activate Document Profiles and OK.

We should always keep an eye on the Info-Palette, especially since we will get more important information about the color of the image there.

Color Sampler Tool

> Activate the Color Sampler Tool.

> Sample Size: 3 by 3 Average.

To better judge color shifts during retouching of a color cast, it is helpful to place a color sampler at a neutral position in the image.

> Set the Color Sampler to the lighter gray of the watercourse: approx. 184/184/193.

The values of the Color Sampler now appear in the Info palette and tell us that we are dealing with a slight blue overhang in this relatively color-neutral zone.

But beware of drawing too quick conclusions. The water surface, of course, reflects the gray-blue of the cloudy sky. So this blue overhang does not have to be a color cast that needs to be retouched.

Now let’s take a look at the third tool that will guide us in both a tonal correction and a color correction: the Histogram.

Histogram

> Show histogram palette: Compact View.

The histogram displays the tonal distributions of our image in the form of multiple, overlapping graphs. What might be a bit confusing at first, soon turns out to be an indispensable high-end feature for any tonal value correction and color correction.

What can be clearly read in the image is also told to us by the histogram:

• We are dealing with a so-called average key image. This means that the tonal distribution is more center weighted.
• There are tonal values in most tonal value ranges. In some areas more and in others less.
• We are not confronted with extreme tonal values anywhere. In fact, we find that in both the shadows range (left) and the highlights range (right), none of the graphs come close to the endpoints of pure black and pure white.

Basically, based on this analysis, we already know what to do. But let’s take it one step at a time.

Let’s look at two comparative examples to make clear the different qualities and how they show up in the histogram.

> Open exercise files 14a and 14b.

The night shot is a so-called low-key image. We see the histogram concentrated in the shadows range (left). Low-key is not synonymous with bad. It is quite typical for night shots.

However, good low-key images are characterized by the fact that details are still present even in the darkest parts of the image, i.e. that the shadows do not merge into pure black, but have a differentiated tonal value structure.

> Switch to the Info palette, display Proof Color in the right panel.

> Drag the cursor over the left image area.

Unfortunately, we notice almost no details in the forest. The water seems to be still a little bit alive. What can be seen from the fluctuating color values in the Info palette can be confirmed by looking into the color channels.

> Switch into the color channels via cmd+3, cmd+4 and cmd+5.

> Return to the composite channel via cmd+2.

If we temporarily bring the total ink coverage back into view, we see that the darkest zones with a maximum of 330% are within the safe range, but will only appear as pure, undifferentiated black in the print image.

> View Info palette, Total Ink in the right panel.

> Check shadows.

At the other end of the tonal spectrum, in the highlights area, we find very similar deficiencies.

> Check highlights.

In the white zones there are no more tonal values at all. There is nothing more to get out of them.

> Change from Total Ink back to Proof Color.

Expanded View:

> Show Histogram: Activate Expanded View in the palette menu.

In the expanded view of the histogram we get additional information in the form of numbers.

• Mean indicates the average brightness of the image or a selection.
  Low-key images have a low mean value, high-key images have a high mean value, and average-key images have a value that is in the midtone range, around tone 128.
• Standard Deviation indicates how much the brightness values vary.
  The lower, the more similar the brightness values of the image are.
  The higher, the stronger brightness differences exist in the image.
• The Median denotes the tonal value that lies in the middle of the existing brightness values, i.e. not statistically as with the arithmetic mean, but de facto.
• The Pixel value corresponds to the file size, provided that the histogram has been calculated completely. The value shrinks as soon as Photoshop calculates the histogram based only on the image cache. This, of course, is accompanied by the popping up of the cache warning icon.
• Level names the tonal value or tonal value section that is clicked in the histogram.

> Locating the Median in the histogram.

> Selecting a tonal value range in the histogram.

• Count indicates how often the tonal value or tonal values of a section occur below the cursor, in other words: how high the graph of the histogram is at the measured point.
• Percentile indicates the percentage value of all pixels targeted in the histogram with the cursor.
  A low percentage value means that only one tone value and its number have been captured, 100% means that all tone values of the image have been captured.
• If the Cache Level shows the value 1, it means that the histogram has been calculated completely. A higher cache level speeds up the creation of a histogram, but it also increases the inaccuracy in the display of the graphs.

It is also clear from the histogram and its values that we are not exactly dealing with an ideal tonal distribution in this image. Just look at how many tonal values are clipped in the shadows range.

If I go to tone level 0 with the cursor in the histogram, the Count value shows that we are dealing with about 190,000 pixels that are pure black.

> Find level 0 with the cursor in the histogram.

> Switch to exercise file 14b.

In a high-key image there are a lot of bright parts of the image. The tonal values, and therefore also the histogram, are concentrated in the highlight area (right).

The Mean value and the Median are very high, the value for the Standard Deviation is very low. This coincides with the optical findings: the image is very bright and rather low in contrast.

If we look more closely at the right edge of the histogram, we see that despite the brightness, there are still hardly any pure white pixels in the image.

> Activate Rectangular Marquee Tool and draw selection in middle snow area.

> Draw selection with shadows (lower right corner).

> Draw selection in highlights (clouds).

Only just in the clouds we find some absolutely white areas.

> Deselect via cmd-D.

> Show Info palette, watch Proof Color display.

> Check highlights in the clouds and observe values.

Even the very bright areas in the image still show details. This means that we have some leeway for a tonal correction and a color correction in the highlight area to achieve a pleasing result. We could, for example, lighten the snow a little or increase the contrast without running the risk of producing color breaks in the print.

Linear color contrast increase

Let’s return to our average key image.

> Switch to exercise file 13.

We start, as said before, with a tonal value correction.

> Adjustment layer Curves: 70/40 and 195/230.

Since we keep the blending mode Normal, the colors will also increase strongly.

The Info palette now shows us two values per color. The left value represents the color value before the correction, the right one the color value after the correction.

Now let’s move on to the color correction.

Of course you already know how to do color correction. The first thing is to check the color neutrality of the image and correct it if necessary.

Remember: color casts are removed by adding the complementary color.

Color wheel

The complementary color pairs are red-cyan, green-magenta and blue-yellow.

If we want to remove unwanted color casts, we like to use the Curves, but we do not make our adjustments in the composite channel, but in the corresponding color channels.

> Show Histogram.

> Histogram palette menu: Activate All Channel View and Show Channels in Color.

> Activate Color Sampler Tool.

> Create a new(!) Curves adjustment layer to adjust and readjust tonal and color correction separately from each other and to be able to readjust them.

For precise color correction, it is advisable to display the tone value histogram and the color channel histograms separately from each other, rather than overlapping them.

Color improvement can usually be achieved quite simply and quickly by spreading the tonal values of the individual color channels. I.e. we want to make sure that the individual graphs span the entire tone value spectrum.

> Curves: Activate the red channel with Option+3.

> Activate white point by pressing the minus key.

We could now move the white point to the left by pressing the arrow keys to make a classic tonal spread or move it down to reduce the tonal range.

> Hold down the left arrow a little longer and watch the red histogram move and move the white point back to 255.

> Hold down the down arrow a little longer and observe the shrinking of the red histogram and move the white point back to 255.

First we want to linearly increase the color contrast in the image.

> Activate the white point.

> Press the left arrow until the white slider is at the foot of the histogram: 245/255.

> Activate black point by pressing the minus key.

> Press the right arrow until the graph is at the foot of the histogram: 10/0.

We now repeat the same game in the other two color channels.

> Curves: Activate the green channel with Option+4.

> Perform linear color contrast increase in the green channel.

> Curves: Activate the blue channel with Option+5.

> Perform linear color contrast increase in the blue channel.

When we have gone through all three color channels, we force Photoshop to calculate an exact histogram and check again the border areas of the histograms.

The two histograms of the Curves and the Histogram palette correspond to each other. Both show the familiar small warning symbol. This is, as I said, an indication that the histograms are currently being generated on the basis of the cache data. I.e. Photoshop shortens the time-consuming process of histogram calculation a bit and currently delivers only an estimate based on samples.

If you want to know exactly – and that’s what we want to do now – click on the warning icons and force Photoshop to calculate and display exact histograms.

> Click on warning symbols.

Now let’s examine again the color sampler we defined at the beginning.

The slight blue overhang has not changed. That’s fine for now, since it’s not a color cast that needs to be retouched.

This kind of linear color contrast increase is quickly done and gives a usable result in many images, which of course still needs to be fine-tuned.

Fine tuning

And this brings us to an important conclusion from our work with histograms: We use histograms as a tool to help us find the right direction for corrections. This does not relieve us of optical control. What is to happen in image processing must always be examined directly on the image.

Working with the histograms and other aids always takes us only as far as a point from which we can start to make an optical adjustment to the colors.

The color contrast has been increased, strictly speaking we have not yet performed a color correction with it.

For example, I would like to increase the yellow tone in the darker midtones a bit. This would bring some sun and thus warmth into the image.

> Curves: Activate the blue channel with Option+5.

We activate the On-image-adjustment Tool and click into the meadow green to pull the curve down minimally at the right place.

> Activate the On-image-adjustment Tool, place the point in the meadow green and drag minimally downwards.

To exclude the blue of the sky from the correction, we set an adjustment point in the highlight area.

> Set compensation point and use it to raise the highlights of the blue channel.

I think we can leave it at that. Let’s look at the before/after.

> Option-click several times on the eye symbol of the background layer.

> Save As… Bsp13_RGB-Curves.psd.

> Open the unedited version of exercise file 13 again.

Color correction via Lab

A completely different, but sometimes promising color correction option is offered by the Lab mode.

> Image / Mode / Lab Color.

> Create adjustment layer Curves.

Correcting color in Lab mode has two advantages:

• In Lab mode, the colors can be processed completely separately from the tonal values in the image. The tonal values thus remain unchanged.
• In Lab mode, the saturation can also be edited completely separately from the tonal values in the image. So we don’t have to worry about affecting the tonal values when increasing the saturation in the image.

Saturation correction via Lab:

In the first step, we increase the color contrast in the familiar linear way. We go into the color channels and move the tone controls until we have a pleasing color contrast result in the image.

> Switch to the a-channel by Option+4.

> Operate the two sliders: -80/-128 and 80/127.

> Switch to the b-channel by Option+5.

> Operate the two sliders: -80/-128 and 80/127.

As you can see, with a simple color contrast increase, the saturation rises strongly. And we don’t lose any details, because the brightness values of the image are not affected by the increase in saturation. They remain completely untouched in the brightness channel. We can therefore increase the color contrast in Lab mode without immediately having to fear negative consequences for the tonal values.

Since we made sure that the correction of all input values has the same extent, the color tones in the image were also not affected by raising the saturation.

Color correction via Lab:

To add yellow to the meadow green, we need to make a correction in the b channel, because that’s where we can affect the blue and yellow components. We activate the On-image-adjustment Tool and click in the middle of the meadow green in order to determine where we have to drag on the curve to produce the desired change.

> Activate the On-image-adjustment Tool, click into the meadow green.

Since we want to restrict the color correction to a narrowly defined color zone, we fix the rest of the curve with a few auxiliary points. Only then can we use the on-image adjustment tool to give the green of the meadow more warmth.

> Set three fix points.

> Color correction point: 45/85.

Tonal correction via Lab:

Now we take care of the tonal values. I create a new Curves adjustment layer for this. Of course we could do the correction in the L channel of the current adjustment layer. However, I want to have the tonal value correction and the color correction separate from each other, so that we can fine-tune them later with the opacity sliders of the two adjustment layers independently of each other.

> Create adjustment layer Curves.

> S-curve: 25/20 and 75/80.

Now let’s compare before and after.

> Option-click several times on the eye symbol of the background layer.

Now we want to increase the contrast in the meadow a little bit. Therefore we create another adjustment layer.

> Create adjustment layer Curves.

> L channel: Roughly create a preliminary S-curve.

> Switch to the Mask panel and open Color Range.

> Set Fuzziness to 0 and select the meadow green with the Shift eyedropper.

> Moderately increase fuzziness so that the greens are largely selected, but the fence slats in the foreground, the sky and the watercourse do not appear in the selection. Possibly touch up with the Option eyedropper and give OK.

> Adjust the S-curve in the L-channel to perfection.

We could now adjust many more details in the image, but let it go at this point.

Finally, we fine-tune the image using the opacity sliders of the adjustment layers. If one or the other setting is too strong, we reduce it to a more natural level.

> Color contrast: Opacity 80%.

> Tone value contrast: Opacity 80%.

> Tonal contrast green tones: Opacity 60%.

> Save As… Bsp13_Lab-Curves.psd.

And now we compare the result of the tone value and color correction in Lab with the one we made before in RGB mode.

> Switch to the RGB version of exercise file 13.

For this we have to increase the saturation in the RGB image a little bit. We do this with a Vibrance adjustment layer or in the Channel Mixer.

> Create Vibrance adjustment layer.

> Vibrance slider: +70.

> Switch several times between the RGB and the Lab document.

If we are not overdoing it, the saturation can also be increased in RGB mode without leaving an overdriven impression. And all other corrections can also be done in RGB mode to complete satisfaction.

So what could possibly motivate us to make the corrections in Lab mode?

The only thing that justifies a temporary switch to Lab mode is that there we can use the entire Lab color space for our corrections. As I said, the Lab color space is device-independent and overrides all other color spaces. This allows tone and color values to be brought into play that are not available in the RGB color space.

Whether one takes the small detour via the Lab mode must be weighed up from case to case.

Personally, I always consider switching to Lab if the color contrast in the image is to be significantly increased at the same time as a color correction. In Lab it is easy to make colors glow without affecting the tonal values.

Incidentally, a tonal value and color correction does not have to end with the settings made in Lab mode.

> Select all layers and convert to Smart Object.

> Image / Mode / RGB.

> Do not rasterize Smart Object.

We have returned to RGB mode without giving up the achievements made in Lab mode. Even more: by double-clicking on the thumbnail of the Smart Object, we could access and modify all the settings made in Lab mode at any time.

The procedure of color correction in Lab mode is not very intuitive, because there colors are not changed as such, but as color pairings.

Much more obvious are the schemes underlying two other important color correction tools in Photoshop:

• Hue/Saturation is based on HSL.
• Selective Color is based on CMYK.

Color Balance

I don’t think we need to discuss Color Balance in the Advanced Workshop. However, a short note is in order.

> Create adjustment layer Color Balance.

> Select Midtones, Cyan-Red: +15.

We already know the small inconspicuous checkbox Preserve Luminosity from the Photo Filter. It ensures that only the colors and saturation are changed by our action, but not the tonal values.

If we use Color Balance to make a small readjustment to the previous tone and color correction, Preserve Luminosity should be activated in any case.

We have already talked enough about Hue/Saturation. We should be familiar with how it works. Let’s take a quick look at Selective Color.

Selective Color

> Hide adjustment layer Color Balance.

> Create adjustment layer Selective Color.

Here we correct colors according to the CMYK scheme. Selective Color is therefore particularly suitable for removing color casts if the image is already in CMYK mode.

The mode change from RGB to CMYK, as we know, involves color shifts. The gamuts of Adobe RGB (1998) and e.g. ISO coated v2 are not congruent. Sometimes a small readjustment is needed in CMYK mode. And I like to do this with Selective Color.

But the tool also works well in RGB mode.

Four-color printing and its requirements are, as it were, the natural habitat of image editors and graphic designers. Breaking down and defining colors according to their CMYK values is learned and obligatory. Working with Selective Color is therefore highly intuitive for most of us.

If we want to intensify the red of the rope, we clearly select Red from the Color menu.

To strengthen red in the CMYK scheme, we take out cyan and add magenta and yellow.

> Colors: Reds.

> Cyan -30, Magenta +40, Yellow +20.

I exaggerate so we can see better how it works.

Now I want to make the meadow look a little sunnier, so let’s switch to the greens and take out cyan there and add yellow and a little magenta.

> Colors: Greens.

> Cyan -15, Magenta +5, Yellow +20.

And finally we want to make the sky a bit more sky blue and less cyan.

> Colors: Cyans.

> Cyan -20, Magenta -20, Yellow -100.

Once you get the hang of it, color corrections using the CMYK scheme are very easy to do.

We made the correction Absolute, not Relative, and that is my recommendation as well. Adding or subtracting an absolute value from a color means that if we add another 10% cyan to 20% cyan, for example, we get a total of 30% cyan. This is how it works in the press.

A relative correction would not refer to the maximum 100% cyan, but to the amount of cyan present in the image. If we add to 20% cyan, 10% cyan relative, we get a total of 22% cyan. This seems nonsensical to me.

Finally, another possibility for high-end color correction should be mentioned only briefly. Such interventions can of course also be done wonderfully with the Color Mixer of the Camera Raw filter. There, however, according to the HSL scheme.

We have already dealt with this in detail and can now leave it at that.

As is so often the case in Photoshop, we also have the choice between a wide variety of tools for tonal value and color correction. Of course, among image editors there are likes for some and dislikes for others. However, our explorations have shown that all tools have their justification. In the end, one always decides in favor of a certain tool because it offers a small or larger advantage over other tools in a very specific application.

Of course, quickly reaching for the appropriate tool is part of the experience that the image editor must acquire.

> Open exercise file 15.

Skin retouching techniques

One of the most challenging retouching tasks to complete in Photoshop is retouching human skin.

We’ll take a look at a few high-end techniques that can help us tackle this complex task.

But we don’t always have to go straight to the biggest guns to get usable results.

Retouching tools

In many cases, skillful stamping and the use of the Healing Brush and Patch Tool will do the trick.

> Zoom in on the face.

> New empty layer.

> Select Healing Brush or Clone Stamp Tool: Aligned, Sample: All Layers, and remove the larger spots.

For the completion of extensive tasks, you would have to have a lot of patience to get everything perfect with the retouching tools. In addition, you will reach the limits of what is possible with the simple tools for difficult tasks.

The classic retouching tools are therefore mostly used for the completion of rough tasks, for example when it comes to removing moles, scars or pimples.

Why is skin retouching so demanding?

A person’s face is, so to speak, the mirror of the soul. We simply look too closely and immediately recognize whether it has been tricked or retouched. That’s why we have to be particularly careful when retouching skin. The primary goal must be to create a realistic, natural and plausible look.

The techniques we are about to discuss can, of course, be used beneficially in a wide variety of applications. The work on the skin merely shows how complex the retouching tasks can be.

Strictly speaking, retouching should be done before tonal and color correction. I’m only discussing this topic now in the workshop because the complex editing steps we’re about to set require a certain basic knowledge.

Camera Raw provides us with plenty of high-end tools to tackle complex tasks like this. As an alternative to the classic retouching tools in the toolbox, for example, we can use the Healing Tool functions in the Camera Raw filter that we’ve already discussed. I’ve also already discussed the advantages of this approach. Let’s quickly retouch a few spots with the Healing Tool.

> Activate Healing Tool and zoom in on the chin area.

> Activate the Heal function and remove the pimples on the chin.

Once the worst is done, it’s time to improve the microtexture of the skin.

And here, too, Camera Raw has a lot in store for us.

Negative Clarity

A fantastic way to smooth the microtexture of the skin is to create negative clarity. Negative Clarity can be created by using the Adjustment Brush of the Masking function.

> Zoom out to the entire face.

> Activate Masking and select Adjustment Brush.

> Open the More Brush Settings menu: Reset Brush Settings.

Show Overlay (auto) should be active. We do not use the Auto Mask function.

> Check Show Overlay (auto), uncheck Auto Mask if necessary.

Our goal is to smooth the skin areas inconspicuously. To do this, let’s first make the brush settings. We need a medium sized soft tip.

> Size 8, Feather 100, Flow 100, Density 100.

• The soft edge is necessary so that we don’t leave any tool marks when we work.
• When creating the mask, we work with maximum flow.
• And we also choose the maximum for the Density.

What remains to be done now, before we can get started, is to select the maximum, negative value for Clarity.

> Clarity -100.

We click somewhere in the retouching area to set the pin for the following action.

> Set pin in the lower left part of the face.

The pin represents both the mask and the retouch. If the retouching is to be subjected to a correction at a later time, activate the corresponding pin and modify the settings it represents.

Now the retouching of the skin texture can begin. Using the Adjustment Brush we capture all those areas that should be retouched. So by brushing the mask, we set the correction at the same time.

> Smooth out all areas of the face with the Adjustment Brush. Leave out the mouth and eyes.

The work is done quickly and easily. Finally, we reduce the smoothness by moderately increasing the negative Clarity value. The aim is to retain the typical skin structure despite smoothing.

> Clarity -80.

Finally, we activate Show Overlay to check whether we have actually retouched all relevant skin areas.

> Activate Show Overlay (auto) by pressing the Y key and deactivate it again.

> Check before/after by pressing the P key.

The before/after comparison proves that with a combined application of Healing Brush and negative Clarity, even demanding retouching tasks can be accomplished easily. The Healing Brush removes the large spots, while the negative Clarity smoothes the microtexture.

We can now improve the result with the help of a Noise Reduction and/or a modification of the image sharpness.

> Activate Pin again, if necessary.

> Sharpen +40, Noise Reduction -40.

If we increase the image sharpness while reducing the noise reduction, we can bring back lost micro-contrast. In this way, the natural pore structure can be somewhat strengthened again.

If, on the other hand, you want to push the smoothing even further, you use the opposite settings.

Once you are satisfied with the skin’s appearance, check the areas that were excluded from the retouching process to see whether we can also gain something there with the help of the Adjustment Brush. 

For example, we could increase the sharpness of the eye areas a bit and perhaps also work out the structure of the eyebrows more strongly. For this, of course, we use a new Adjustment Brush with completely different settings.

> Create New Mask

> Size 3, Feather 100, Flow 100, Density 100.

> Clarity +20.

> Pin in an iris, brush both eyes and eyebrows.

So when we want to intensify structures, we don’t reach for the Sharpen slider every time. Gently creating a positive Clarity sometimes yields better results.

We could now use many more tools in Camera Raw to further the work on the face. We could put on some blush or color the lips. We could enhance the whites of the eyes or change the eye color. We could intervene in the skin tone and much more. However, let’s leave it alone at this point.

> Apply Camera Raw filter with OK.

> Before/after control by fading out and in the correction layer.

Frequency Separation

Another very efficient retouching method is called Frequency Separation.

Since the procedure is a bit more complex, let’s think about what it’s all about and why it makes sense.

Remember the effects we could achieve with the simple retouching tools like the Stamp Tool and the Healing Brush.

• The Stamp Tool clones the captured parts of the image without regard to the environment that is affected by the retouching. So: the texture and the tone values and the color values and the color contrasts and the saturation values are transferred 1:1. Without leaving work marks, this only works in absolutely homogeneous areas.

• The Healing Brush is a little more considerate. The Healing Brush also clones the texture and the tone values and the color values, etc., but the result is adjusted to the environment at the end of the repair process. Strictly speaking, the tone values and the color values of the environment are transferred to the patch. This creates a more inconspicuous situation, but one that is ultimately just as artificial as the one that can be created with the simpler Stamp Tool.

If we could edit the texture and the colors with all their properties separately, the two aspects would not interfere with each other during retouching. And that’s exactly what Frequency Separation allows us to do.

> Hide Camera Raw layer.

Let’s take a closer look at the natural skin.

• On the one hand, we find in it larger imperfections such as pimples, wrinkles and scars, alongside finer micro-level contrast differences such as pores and hairs.
• On the other hand, we notice darker and lighter areas, different hues and degrees of saturation, color contrasts and color spots.

We now want to separate these two complexes, the texture complex and the color complex.

We start by creating two duplicates of our image. In the lower layer we want to work on the colors, in the layer above, separately, we want to work on the texture.

> 2 x duplicate background layer.

> Name lower layer: “Colors”, name upper layer: “Texture”.

> Group the two layers, name of the group: “Frequency Separation”.

We start by removing all texture aspects from the colors layer.

> Hide texture layer, activate colors layer.

> Filter / Blur / Gaussian Blur: 5 Px.

To do this, we blur the subject of the color layer just enough so that contrast variations such as pores, hairs, etc. are no longer visible. Now only the colors are in the color layer.

Now we have to remove the colors from the texture layer. This requires a calculation process, which we can do in the Apply Image dialog.

> Show and activate the texture layer.

> Open Image / Apply Image.

Step 1: We select the layer whose values we want to subtract from the active layer in the Layer menu.

Step 2: To subtract the colors set the Blending Mode Subtract.

> Layer: “Colors”, Blending: Subtract.

Step 3 and 4: With Scale and Offset we define the parameters of the so called high pass effect.

> Scale: 2, Offset: 128.

• Our image is in a bit depth of 8 bit/channel. The Blending Mode Subtract, Scale 2 and Offset 128 are perfect for this.
• If you want to achieve the same effect in a 16-bit image, you have to choose the Blending Mode Add, Scale 2 and Offset 0.

For the rest, we won’t think about it any further.

> OK.

Now we have the basic setup of the Frequency Separation. We just have to change the Blending Mode of the texture layer to Linear Light. The sense of this last measure is that all pixels of medium gray are hidden and only the pure textures are visible in the layer.

> Blending mode Texture layer: Linear Light.

Done. We now hide the group briefly and show it again.

> Hide group and show it again.

No difference to the background layer to see. But what we actually have with this setup is the intended separation of the textures of the image from the colors of the image.

> Hide individual layers and show them again.

Now we can get to work on the two separate complexes separately.

First we take care of the colors, i.e. color variations and color stains in the broadest sense. We want to achieve a certain smoothing, a certain calming of the complexion. For this we need to put measures in the colors layer.

I’ll exaggerate a bit in the following steps so that you can see the effects better. In fact, the main directive for interventions in the skin is: caution and restraint.

> Activate Lasso, Feather 30 Px.

> Select forehead area.

> Filter / Blur / Gaussian Blur: 8 Px.

The soft lasso edge ensures that we don’t create hard transitions between the retouched areas.

We control the amount of Gaussian blur applied directly in the image, not in the preview window of the dialog. What the preview window shows is the actual effect in the colors layer.

In the image, the impression of sharpness is preserved because, after all, the textures and thus the sharpness are in a different layer and are not affected. For this reason, we can also ignore the fact that we included a few fine hairs in the selection.

We now gradually capture all the relevant skin areas of the face and soften the color zones with a specific setting of the filter in each case.

> Select skin areas successively and blur them.

> Gaussian Blur: 8 to 20px.

Once we have smoothed the complexion, we move on to retouching the texture. And here we also resort to a very traditional and simple tool. We can use the Clone Stamp Tool in the texture layer completely safely, because the hues, the color variations and the saturation are not affected by it. Only the texture is cloned.

> Activate texture layer.

> Activate Clone Stamp Tool: round, soft tip.

> Options bar, Sample: Current Layer(!).

> Brush away pimples, scars and finally the forehead wrinkle.

The small detour of creating a Frequency Separation enables us to do complex retouching perfectly with the simplest tools. I think the small amount of time spent creating the setup is worth it.

> Hide and show group for before/after.

The Frequency Separation set-up can also be used for other corrections.

• For example, if we want to adjust the skin color, we can do this by inserting a corresponding color correction layer above the colors layer.
• If we want to edit the texture further, e.g. blur the pores a bit, we can do this by inserting a noise reduction layer above the texture layer.

Change skin tone:

> Insert adjustment layer Selective Color above the colors layer.

> Reds: Cyan -15, Magenta +20, Yellow +20.

> Yellows: Cyan -20, Magenta +10.

> Invert layer mask.

> Activate soft large brush and apply blush.

> Blending mode: Color.

Blur microtextures:

> New empty layer above the texture layer.

> Blending Mode: Lighten.

> Make an intersection, since we don’t want to lighten the colors as well.

> Foreground color: Medium gray RGB 128-128-128.

> Activate soft large brush, reduce flow to 5% and lighten pores.

I think it has become clear what a powerful retouching tool Frequency Separation is in Photoshop. What may seem a little complicated at first turns out to be quite simple and highly effective when used.