Applying Color Theory Inside Photoshop

Here is a rough outline I did for a composite I worked on last year when I was in Hawaii. As you can tell, each photo has a color cast, but the color cast for each is different. If I'm going to create a cohesive piece, these all need to have the same colors.

If you have the Info panel open in Photoshop, then it will show you the RGB values (or CMYK values, if you work in that color space) for any particular area of an image.

I picked one photo that looked as if it had the right color cast and made that my "control image". I looked at the RGB values in the Info panel and tweaked each of the other images using Color Overlays until I was seeing similar RGB values in my new photos. You can do this by going to Layer > New > Fill Layer, and choosing a color that is on the opposite side of the color wheel from the one you are trying to correct for. Then lower the Opacity until the RGB values read the same.

By understanding how all the colors work together, I was able to adjust every underwater photo to match the control image. Once everything matches, then it's just a matter of blending using layer masks and a brush, and applying creative color adjustments on top.

Conclusion

In this tutorial you've learned the basics of color theory. You now know how additive and subtractive colors work, and you've seen some examples of how you can use this theoretical knowledge to create better photographs.

When has a deeper understanding of RGB and CMYK helped you in your photography? I'd love to know in the comments.