Setting the right contrast and color balance in an image is an essential part of any digital image developing workflow. The correct contrast and color balance should be established as early in your developing workflow as possible. Contrast and color problems that are left unmitigated will become compounded as successive adjustments are made to an image, making them much harder to correct later in the workflow.
In my workflow classes and video tutorials I show how to start by setting a foundation for contrast and color balance while making preliminary raw adjustments in Lightroom or Adobe Camera Raw. Then I fine tune my global contrast and color balance as one of the initial steps in Photoshop. When making raw adjustments I don’t try to perfect contrast and color balance in Lightroom or Camera Raw. Rather, I get them close and then fine tune them in Photoshop where there are many more tools at my disposal and I can be much more precise. When setting my contrast in Lightroom or Adobe Camera Raw I prefer not to set complete black and white points. Instead I opt to leave some “wiggle” room on either end of the histogram. This leaves some latitude for applying more targeted adjustments later in Photoshop, as you will see.
Proper contrast in most images is obtained by setting a luminosity black point (a small portion of the image that is completely black) and sometimes a luminosity white point (a small portion of the image that is completely white). Images without a black point and a white point can appear muddy, hazy and flat.
Some images are low contrast by nature, such as images taken in the fog. If your artistic intent is to retain low contrast in an image then setting a black and white point is probably not the right choice.
Proper color balance is obtained when shadow, midtone and highlight color casts or color shifts have been corrected and objects that are neutral gray appear neutral gray in the image. In images intended to have “white light” or “daylight” colors it is usually appropriate to set the correct color balance in the shadows, midtones and highlights.
There are many ways to work with contrast and color in Photoshop. The Brightness/Contrast and Color Balance Adjustments are tools specifically designed for working with contrast and color respectively. It is also possible to make similar adjustments in slightly different ways using combinations of the Levels, Curves, Hue/Saturation and Selective Color Adjustment tools. Photoshop even includes Auto Contrast and Auto Color adjustments, but I find that these rarely get it right and must be done on the background layer or a copy of the background layer. I would recommend sticking with adjustments you can make using separate Adjustment Layers so that your adjustments are non-destructive.
Most of the techniques for correcting contrast and color balance involve working with each component separately. While these methods can be very accurate and flexible they are often time consuming and require knowledge of color theory, a degree of skill and a good eye. The approach that I use most often, one I call the “global contrast/color correction technique”, is quick, requires very little knowledge of color theory and adjusts for both contrast and color balance at the same time.
Start by opening a raw image file in Photoshop. After you have done spot clean up, cloning and any perspective adjustments that are needed, create a Levels Adjustment Layer (Layer>New Adjustment Layer>Levels). In the Levels dialog select the Red Channel from the drop down menu. Now slide the Shadow slider and the Highlight slider so that they just touch their respective edges of the histogram. You have now set a black point and a white point for the Red Channel.
Now select the Green Channel from the Channel Menu and repeat the process.
Finally, select the Blue Channel and do the same one more time. Return to the RGB Channel and fine tune your midtone slider as needed for image brightness.
Toggle the Levels Adjustment Layer on and off by clicking the Eye icon to see the results of your adjustment. If your image had poor contrast or a color cast you should now see a marked improvement in both contrast and color balance (see examples below). By setting a dark and light point for each color channel you have essentially killed two birds with one stone. You have set an overall black and white point so that the image has proper contrast and you have also neutralized shadow and highlight color casts at the same time. If you feel that you still have an unwanted color cast in your midtones after setting the blacks and whites you can go back into each color channel and adjust the midtone sliders to further fine tune the color. You can see that if I had not left some shadow and highlight room on either end of the histogram in your raw conversion that this technique would not have worked.
Certain light creates a pleasing color cast that you may not want to neutralize. Warm, sunset or sunrise light is an obvious example. By neutralizing a warm sunrise color cast you will make the light look like mid day light while making the shadows in the image look too blue. If you have an image in which you do not want to neutralize a highlight color cast you can set the shadow contrast and color by moving the sliders on left side of the histogram in each color channel and then selectively tune the white and midtone sliders of each color channel until you get the desired color cast.
There is also a more precise version of this technique that can be done by using a Threshold Adjustment Layer to set markers at the exact black and white points in an image and then balancing the colors close to 0 and 255 at each of those two points using a curves layer, but most often I find the Levels method demonstrated here works well enough.
Not having the correct contrast or color balance in an image can really detract from the impact you intended it to have. To ensure that your images are not flat or dull and that they do not have distracting color casts or contamination, make sure to establish the right contrast and color balance early in your workflow before it becomes compounded by further developing adjustments.
To learn more about my fine art digital image developing workflow you can check out my video tutorial series.