This is the full text of an article that was recently published in Photo Technique magazine, PhotoTechMag.com. (there may be some minor differences in the text)
Selective Color Adjustment in Adobe Photoshop, by David Saffir
There are quite a few ways you can edit color in Photoshop, even down to the colors of leaves on a tree. The advantages? You can target specific parts of an image for a simple color boost, change the color completely, add a color tint or color cast, improve dimensionality and more. I define selective color adjustment to also include selective color replacement.
I encourage the use of Photoshop, because many of these techniques can be applied to a new layer, or an adjustment layer, or a series of layers. This gives you maximum flexibility in editing although it can sometimes increase file size. I’ll review several methods I use, but keep in mind that there are also many more color adjustment options in Photoshop.
Figure 1 (iStockphoto)
Some of the tools in Photoshop require working knowledge of the color wheel. Figure 1 is a modestly stylized version of a color wheel.
Note that that color blue is opposite yellow, red opposite cyan, and green opposite magenta. If an image has a blue color cast, adding an appropriate amount of yellow can balance the image and give a more neutral appearance. Adding even more yellow would result in a yellow color cast, or “warmer” appearance.
Color Balance Adjustment Layer
The Color Balance adjustment layer is a powerful tool: you can activate this from the Layers Panel, or go Layers>Adjustment Layer>Color Balance. Note the “warm tone” in this image. (I think of the Color Balance panel as a selective color adjustment, because you can balance the image using the color wheel as a guide, and also work selectively among highlights, shadows, and midtones).
I suggest that you work in small steps. For example, add a small amount of blue in the highlights, then switch to midtones, and repeat the cycle until the image is pleasing. Figure 2 is the ‘before’ photograph. In Figure 3 I’ve “added” blue to the image in the highlights and midtones, pushing it toward a more neutral appearance. In this case, I’ve added a bit more blue than necessary just so you can see the effect on this printed page.
Selective Color Adjustment Layer
This option offers a wide range of combinations. First, the panel offers a drop-down menu that contains six main colors that can be adjusted: red, yellow, green, cyan, blue and magenta. (Familiar, aren’t they? These are primary points on the color wheel). It also offers adjustments for white, neutral and black. Figure 4 is the ‘before’ photograph.
In a way, this panel is a “cousin” to the Color Balance tool set. It offers much more flexibility, however—examine the example in Figure 3—we have the option of increasing or decreasing the amount of cyan, magenta, yellow, or black in any of the choices offered in the drop down menu. In this case, (Figure 5) if we select red and increase cyan, its opposite on the color wheel, the reds become subdued. Small steps are best.
You may find it necessary to combine adjustments and/or corrections to get the look and feel you want. If you change the layer blending mode to “color” you can create multiple adjustment layers, and stack them for cumulative effect.
This is one of my favorite tools in Photoshop, particularly when editing landscape or still life images. It is frequently used by photo retouchers to change hue and saturation in commercial photography—and it can be adapted to use in landscape and scenic photography to add depth, dimensionality and tone separation to an image.
Here’s an image (Figure 6) that I took near the California Poppy Reserve some time ago. Basic adjustments, such as levels and curves have been completed. Partially overcast conditions make colors on the ground looks a bit subdued, and a little flat.
Next, we’re going to open the Replace Color panel (Image>Adjustments>Replace Color). At the top of the panel, enable “Local Color Clusters”. This will improve your control of any changes, in many cases limiting those changes to a patch of color, or a patch and its neighbors.
Next, use the left hand eyedropper to select a color area. In this case, (Figure 7) I’ve selected the yellow patch in the distance, on the left hand side near the horizon. I’ve also pushed the Fuzziness slider to the right, to include some of the colors in the grass. (Note that I’ve enabled Selection view in the panel, which provide a black/white view similar to the Threshold tool—the white areas show the selection quite clearly. You can use the +dropper tool to select additional areas—but take care to limit your selections to colors that are close to your original choice).
I then increase the saturation in the selected area. Note the change in the yellow areas of the photograph, Figure 8.
If you want to use a different color, you can move the Hue slider to the right or left. Keep in mind that this adjustment is very intense and challenging to control. I prefer to use the Color Picker, which can be accessed by double clicking on the color square just to the right of the Hue slider. You can select almost any color via mouse click, or by typing in the RGB or HSB numbers for a color (Figure 9). The Lightness slider can also be useful—particularly if you’ve increased saturation in an area, and it’s looking a bit too prominent. You can pull the Lightness slider to the left just a touch to subdue it.
You can continue this process of selected color modification in targeted areas. Note the changes in the grass and flowers on the left side of the image—and now, off in the distance, you can see a stronger hint of the orange color of the poppies in bloom. (In Figure 9, I’ve exaggerated the effect a bit to improve visibility on the printed page).
Final image – all images © David Saffir 2010
It takes a light touch to get well-controlled and realistic results. Color intensity, dimensionality and tonal separation can be improved. Practice is the key to success—and of course, take full advantage of multiple layers to mix and match and create your final image.