Photoshop makes color correction of your scanned film photography pretty easy, but it also provides quite a few different ways to do so. In general, color correction can be done by simply eyeing the photograph, but the overall process is greatly assisted by the histogram. The histogram is found in the Window menu. The left side of the histogram represents the shadows, the right side represents highlights, and the middle is the midtones. The channel of the histogram can be changed to show “Color,” allowing you the ability to see if any particular color dominates the others.
To begin correcting colors you have two options:
- In the Image menu, hover over “Adjustments” and you’ll see many adjustments you can make. The adjustments are made only to the layer selected and cannot be edited once made (aside from undoing the work and starting again).
- In the Layers menu, click “New Adjustment Layer” and you’ll be able to make many of the same adjustments. The advantage to this method is that you will always the have the ability to edit the adjustment layer or delete the adjustment entirely. This option can also be found along the bottom of the layers panel by clicking “Create new fill or adjustment layer” and then selecting the adjustment.
Levels (Ctrl + L on Windows or ⌘ + L on Mac)
Levels is one of the most basic, and simplest, adjustments to make and mainly affects contrast of the image. You are provided with three sliders and the histogram. The left slider manages the shadows, the right manages the highlights, and the middle manages the midtones. As a result, moving the left slider to the right darkens the shadows, moving the right slider to the left increases the highlight intensity, and moving the middle slider left darkens the photos and moving it right lightens it. You can also select color channels to edit the intensity of each individual color. Note, if the image is black and white in grayscale, the levels adjustment only provides the channel option for gray.
Photoshop also provides an Automatic Levels option. This option can provide results that are good enough for you but shouldn’t be relied on to do everything.
Color Balance (Ctrl + B on Windows or ⌘ + B on Mac)
The color balance adjustment does just what the name suggests, allows you to adjust colors to balance them out a little. If you are striving for natural color then this tool should be used sparingly as it can quickly and dramatically change the colors of your image – even the most slight adjustment can swing the color balance the wrong way. The tool allows you to individually select a tone balance for Highlights, Midtones, and Shadows. If a bright sky has too much blue, or even too little blue, using the Highlight balance can change that.
Like Levels, Photoshop also provides an Automatic Color Balance option.
Curves (Ctrl + M on Windows or ⌘ + M on Mac)
While Levels and some minor color balance may work for you, Curves is a much more powerful tool to use. It is similar to levels in that there is a control for shadows, midtones, and highlights and also gives you the ability to adjust the entire image or specific channels. But the strength of Curves lies in the ability to set your own points on the curve line. You can click anywhere on the line and pull the curve up or down – pulling up will increase the highlights and pulling down will increase the shadows.
For simple step-by-step instructions using Curves to fix a color image, see 9 steps to color correction using Photoshop curves.