Color Correction Technique
Image: Dune Buggy For Color Correction.
Start by opening an image that needs color correction.
This lesson will teach you how to color correct an image with the eyedroppers of "Levels". Start by having the "Info" palette visible. If it isn’t visible, choose: Window/Info. Next, make sure the eyedropper tool is set to three by three average.

Now that the eyedropper is set to 3x3 average, open up "Levels" (image/adjustments/Levels).As you can see, the histogram looks pretty good. Even though the histogram looks good, it doesn’t reflect that the image is off color, and needs to be color corrected. This is where some people have a problem. Is the image too red, or too magenta? With this technique it doesn’t matter.

Once you learn how to color correct "by the numbers", you are no longer monitor dependent. The numbers don’t lie. Remember that a clean black area of the image has equal RGB numbers. A clean white area of the image also has equal RGB numbers.

Hold down the "Shift" key and click on any dark part of the image that should be neutral in color. This will set a color sample point.

Now hold down the shift key and click on any light part of the image that should be neutral in color. This will set a second sample point.

The color sample point places a set of values in the info palette.
Let’s start with the dark sample point.

As you can see, the RGB values are different. This is why the dark tones of the image are off color. A good clean color would yield RGB values that are the same. Look at the lowest value. In this example, The Green value of 53 is the lowest. That’s the value we’ll use.Double click on the Black eyedropper and set the RGB values to 53,53,53 and click Ok to the Color Picker.

Now take your mouse out in the image and click on the #1 sample point.

The image should look a little better. Don’t be too concerned if the values are off by one number. The RGB numbers on the left side are the values before your correction. The RGB numbers on the right side are the values after your correction.

Now lets clean up the whites of the image. The RGB values of the sample point are: Red 244, Green 240 and Blue 242.

Double click on the white eyedropper tool to bring up the color picker. This time take the highest RGB. The highest value is 244. Type in 244 for the Red, Green and Blue values and click OK to the color picker. Now take your mouse out into the image and click on the #2 sample point. At this stage the image should look pretty good. Click OK to "Levels".

Choose "No" to saving the new target values.
The color sample points save with the image. They will not print in the image. The only time they show is when the eyedropper tool is chosen. I like to keep them. To remove them, have the eyedropper tool chosen and hold the shift key down, and drag them off of the image.The next step is optional.

The middle eyedropper of "Levels" can also be used to color correct the middle tones of the image. The middle eyedropper is be used on areas of the image that should be neutral or lacking in color (a shade of gray). Open "Levels" one more time. This time highlight the middle gray eyedropper. Take your mouse out into the image and click on any middle shade of the image that should be neutral (a shade of gray). You don’t have to set any values to the middle gray eyedropper. The preset values for the middle eyedropper are 128,128,128. Click on an area in the image that should be neutral. If you don’t like the look, just click on another area. Each click will yield a slightly different color to the image. If the middle eyedropper doesn’t yield a better color, just cancel the levels box. I like to fish around the image with the middle eyedropper to see if I can get a color balance that I like. If it doesn’t look good, just cancel the levels box.

Once you get this technique down, there isn’t an image that you can’t color correct. The beauty of this technique is the numbers don’t lie.