Photo Color Correction

Adobe Photoshop Tutorials

Evaluation

Photo color correction begins after photo color evaluation, answering the $64,000 question, "What's wrong with this picture?"

The first challenge in photo color evaluation outside a tutorial is basic: there is no context. You cannot compare an image to what it could look like, or what it should look like, and make the corrections. There are no before and after pictures side by side telling you where to make the changes, and how different your image can look.

Without context how can a photo be evaluated? Each picture is different, but there are guides to pinpointing general and specific problems.

Start with the general and move to the specific. Is there a color problem which affects the entire photo?

Color Cast

The technical term for one color problem affecting an entire photo is color cast. The definition of a color cast is: "An overall color imbalance in an image, as if viewed through a colored filter."

It is when one dominant color appears as a trace in all the other colors in a photograph. The predominance of a particular color ruins the whole image. It is like the proverbial rotten apple that ruins the barrel.

Many times a photo or scan will have a single-color cast, where, for example, the entire picture has a blue tint, or a red tint, or a yellow tint. There are also color casts which include two colors or where two colors dominate, like yellow/green as opposed to a pure yellow cast.

Photoshop can remove a color cast of any color using one or more of the Photoshop color filters: Levels, Curves, Color Balance, Hue/Saturation, Selective Color Options or Channel Mixing.

Background Check

Similar to the color cast which covers the entire image is the "cast" which covers the entire background. The original photo, for example, has a white background, but the scan does not produce a white background.

Sometimes the background will have a single faint color, a very light blue, a very light green, or a very light red, for example.

A scanned photo may not have an obvious color in the background; it can have little if any color but still look dirty (a flat gray), or there are lots of stray pixels. This is a very common problem. It eats up file space and doesn't look professional. Therefore it should be one of the first things to check.

It is not always easy to see if a background is pure white before (or after) color correction. It depends on the settings and quality of the monitor. But there is a simple way to check the background color to confirm it is pure white.

If you click on the background with the magic wand, for example, the entire area should be selected. If it isn't, there's the proof of the problem. The magic wand needs to be set at a low number. (Default is 32.) The lower it is the more accurate the reading.

Press Enter after selecting the magic wand to pull up the magic wand dialog box. The number is the number of colors the magic wand will select. The wand will select similar colors/shades to the exact place where the wand is clicked on an image.

If the wand is set to 1, and the background is pure white, i.e., one color, the entire background will be selected.

There's another way to select an area of one color. It doesn't use the magic wand tool, and it doesn't require clicking on any part of the image, but it selects every pixel of a specific color or specific color range in the image.

Color Range

Photoshop's color range selection feature is similar to the magic wand tool in that it selects a designated range of colors, but it works better than the magic wand tool when you need to select the entire background at once, without multiple clicks to join together each background area.

Select > Color Range

Once the dialog box comes up, you can choose the range of colors you want to select, using the Fuzziness slider. If you set Fuzziness to 1 and click on the background, (then click OK), the selection should cover the entire background.