Selective Color Saturation

Article and Photography by Ron Bigelow

www.ronbigelow.com

Photoshop CS4 Used in this Tutorial

One of the first things that a photographer learns in Photoshop is how to adjust image saturation with the Hue/Saturation adjustment layer. Hue/Saturation is such a great tool. When used properly, it can produce significant improvements in image impact. In addition, it is easy to use. Simply moving the Saturation slider instantly changes the image saturation. Unfortunately, the tool's ease of use can also be its weakness. It is so effortless to boost the overall saturation of an image by merely moving a single slider that many photographers never go deeper to learn the full potential of the tool. Thus, they never unleash the full power of Hue/Saturation to optimize photographic images.

The key here is that moving the Saturation slider increases the overall saturation of an image. That is fine for some images. However, what if it is necessary to enhance the saturation of a specific range of colors in an image? In other words, perhaps it is necessary to saturate the reds but not the other colors. What if the demands of the image editing are even more exacting? For instance, it might be necessary to increase the saturation of some of the red hues but not the other reds. Actually, that presents no problem. The technique examined in this article will allow the full power of Hue/Saturation to be used to fine tune specific colors for improved image optimization.

Examining the Colors

Figure 1: Fall Color Image

Here is an image that has just such color saturation issues (see Figure 1). This fall color image has various trees with different colors. The trees have three main colors, yellow, green, and red. It is obvious that this image needs additional saturation to make the image come alive. The problem is that not all of the colors need the same amount of saturation. A closer examination shows why.

Figure 2: Adjustments Panel

Hue/Saturation accessed by clicking on the Hue/Saturation icon on the Adjustments panel (see Figure 2).

Moving the Saturation slider to a setting of 15 (see Figure 3), the reds look about right, but the yellows and greens need more saturation (see Figure 4).

Note: Move the mouse over Figure 4 to compare the image with a
saturation setting of 15 to the original image with no saturation.

Figure 3: Saturation Setting of 15
Figure 4: Image with Saturation Setting of 15

 

At a setting of 25 (see Figure 5), the yellows look good, but the light green on the foreground trees could still use a little more saturation (see Figure 6).

Note: Move the mouse over Figure 6 to compare the image with a
saturation setting of 25 to the prior image with a saturation setting of 15.

Figure 5: Saturation Setting of 25
Figure 6: Image with Saturation Setting of 25

 

At a setting of 35 (see Figure 7), the light greens now look nice, but the other colors are over saturated (see Figure 8).

Note: Move the mouse over Figure 8 to compare the image with a
saturation setting of 35 to the prior image with a saturation setting of 25.

Figure 7: Saturation Setting of 35
Figure 8: Image with Saturation Setting of 35

 

So, in this image, a saturation setting that works well for one color does not work well for the others. In a case like this, what can be done?

Adjusting Yellow

Figure 9: Reset to adjustment defaults Button

First, the Reset to adjustment defaults button on the Hue/Saturation dialogue box (see Figure 9) must be clicked to set everything back to the default settings.

Figure 10: Pop-up Menu
Next, the pop-up menu is clicked (see Figure 10), and Yellows is selected.

If the Saturation slider is moved to the right, the yellows start to become more saturated. Now, during this step, it is necessary to saturate only the yellows and none of the other colors. That brings up a question. How is it possible to ensure that only the yellows are being saturated? Here is the trick. The saturation slider is dragged to the right as far as it will go (see Figure 11). Okay, the image is now ridiculously over saturated (see Figure 12). However, that is fine for now; the Saturation slider will not be left in this position for long. An examination of the colors shows that the yellows are saturated, but so are the greens and the reds. Clearly, this is not acceptable. At this point, the saturation needs to be adjusted so that it affects only the yellows.

Figure 11: Yellow Channel Full Saturation
Figure 12: Image with Yellows Fully Saturated

 

Figure 13: Adjustment Sliders
This is where the adjustment sliders at the bottom of the Hue/Saturation panel come into play. It is important to understand these sliders. Notice the two rectangular sliders. The colors between these two sliders are fully saturated up to the amount determined by the Saturation slider above. Now, notice the two triangle sliders. The saturation of the colors between the rectangular sliders and the triangle sliders falls off as the colors move away from the rectangular sliders and toward the triangle sliders. The colors outside of the triangle sliders are not saturated at all.
Figure 14: Subtract from Sample Eyedropper

These sliders are the key that will prevent the reds and greens from being saturated. All that needs to be done is to fine tune the color range with the sliders. The greens will be handled first. Now, there are a couple of ways that this can be done. One way is to choose the Subtract from Sample Eyedropper tool (see Figure 14) and click on the greens that we do not want saturated. This is a quick way to adjust the color range. However, it is not a very accurate method; adjusting the slider directly is a far more accurate method. So, that is the method that will be used with this image.

If the color range is examined, the problem becomes obvious: the right sliders let some of the greens into the color range. That can be fixed by moving the sliders inward.

The sliders are moved inward until the greens are no longer within the color range and the greens desaturate in the image. The reds are treated in a similar manner (see Figure 15). Figure 16 shows that the yellows are saturated, but the greens and reds are not. This is exactly as desired.

Figure 15: Reds and Green Not Saturated
Figure 16: Image with Reds and Greens not Saturated

 

The last step for the yellows is to find the setting for the Saturation slider that produces the amount of saturation that is desired. A setting around thirty or so seems to work well (see Figure 17). Figure 18 shows the image with the final yellow saturation settings.

Figure 17: Final Yellow Saturation Settings
Figure 18: Image with Final Yellow Saturation Settings

 

Of course, there is still more work to do. The saturation of the reds and the greens needs to be adjusted. The Reds will be done next. The pop-up menu is accessed again, and the red channel is selected. The procedure is done in exactly the same manner as with the yellows. Figures 19 shows the final adjustments for the reds and Figure 20 shows what the image looks like after the reds were adjusted.

Figure 19: Final Red Saturation Settings
Figure 20: Image with Final Red Saturation Settings

 

It is now time to saturate the greens. Selecting the green channel from the pop-up menu and moving the Saturation slider all the way to the right gets the process started.

Figure 21: Two Shades of Green

However, with the green channel, there is a problem. It turns out that there are actually two major shades of green. The leaves on the foreground trees have one shade of green. The dark green of the pine trees in the background are a different shade of green. Both of these greens are currently being saturated. To properly saturate this image, it is necessary to saturate the light green leaves of the foreground trees but not the dark green of the pine trees.

Okay, so why shouldn't the green of the dark pine trees be saturated? There are actually two reasons. First, pine needles are not very saturated in real life. So, making them saturated in the image makes the pine trees look odd. Second, the viewers’ attention needs to be focused on the foreground trees with the fall color. Since saturated colors drawn peoples’ attention, the viewers’ attention will naturally be drawn to the saturated fall colors. This is as it should be. However, if the green of the pine trees is saturated, this will make the background compete for the viewers’ attention. In other words, it will tend to draw the viewers’ attention away from the fall colors. This will weaken the image.

So, the sliders need to be adjusted to remove the darker greens. The result is that only a very narrow range of green is saturated. After the Saturation slider is adjusted, the final settings for the greens appear as in Figure 22. The image after all of the saturation adjustments is shown in Figure 23.

Figure 22: Final Green Saturation Settings
Figure 23: Image with Final Green Saturation Settings

 

Final Image

Figure 24: Final Layers Panel

That pretty much wraps up the saturation work. To finalize the image, a Curves layer was added to enhance the contrast. Figure 24 shows the final Layers panel. Figure 25 shows the final image.

Figure 25: Final Image

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