In Correcting Colors Part 1 we learned how to adjust and fix the color cast on images using the levels tools, individual channels, and our eyes. Now that we understand how the levels tool works (hopefully, somewhat), we can fix images. However, relying on imperfect tools such as our monitors which can fall out of calibration, and our eyes means that correcting colors may not be as precise as we would like. (and picky photographers like precision!)
The answer is simple. We need something that can tell us how much of a cast we have so we can counter it and effectively and precisely adjust our images. In this tutorial, we will cover the color sampler tool and use it to pick points and adjust our image accordingly. Note : We will make the assumption that we know what colors the points we select SHOULD be. For example, it's probably only wise to select neutral points (grey), where we know that red will equal green and blue (red = green = blue).
Tip!
Larger Sample
Using the eye dropper tool on a single point is risky because of color noise. Theres a strong chance you'll randomly click on a point that deviates from the average color more than the others. Because of this, it is wise to use a larger area to sample from by using a 5x5 average point instead of a single point. Just right click with the eye dropper tool and go down and click on 5x5!
Grey Card Users
If you're using a grey card, true grey should be 200/200/200!
Using Histograms to fix a muddy image!
Picking a point that SHOULD be black can be a good way to make sure your image has a black point and isn't too muddy. If, for example, your deepest shadow has RGB values of 12/12/13, you know that your image doesn't have a black point and you should clip the left side of your histogram to account for that.
