There is a lot to say about color theory, but I won’t do that. :) I will keep it relatively short and explain how you can exploit the basics of color theory and color harmony theory to create a photo that is more appealing to the eye.

The history of color theory goes back to (at least) the 18th century, when it was believed that all colors could be created by mixing the three colors red, yellow and blue (RYB). These three colors are called primary colors. In the late 19th century, scientists found out that the best primary colors for the human eye are actually red, green and blue (RGB) instead of RYB. The reason is simply that combinations of RGB lead to the greatest range of colors visible to the human eye. Secondary colors are colors that can be created by mixing two primary colors. For the RGB primary colors, the secondary colors are yellow (green + red), magenta (red + blue) and cyan (blue + green). The tertiary colors are combinations of primary colors and secondary colors.

The so-called color wheel is a schematic organization of the primary, secondary, tertiary colors and other colors that can be created from the three primary colors. The primary colors are equally spaced around the color wheel. In books and on the internet you might mostly find the color wheel for RYB primary colors, but here I use the RGB color wheel as RGB are the best primary colors for the human eye as explained above.

So color theory has a long history. The theory and research on color harmony is also quite old and research is still ongoing. Let me first explain what color harmony actually means. Color harmony refers to the property that certain combinations of colors are aesthetically more appealing than others. The research that was done on primary colors and which are the best to the human eye I consider as hard science: the research was quantifiable and objective. Color harmony theory however, is much more soft science. There is no theory that tells you exactly what color combinations to use to make the most appealing image. Some color harmony theories are contradictory; there is no consensus about color harmony. And one of the main reasons for that is probably that color combinations that are aesthetically most appealing are dependent on human race, gender, age, culture, etc. Basically, what is aesthetically most appealing differs per person. However, the good news is that there are some basis rules for colors combinations that are on average aesthetically (most) appealing.

Color combinations that are aesthetically appealing include combinations of:

- Complementary colors, i.e. colors that are opposites on the color wheel

- Split-complementary colors or compound harmony colors, i.e. a variation of the complementary color scheme

- Triadic colors, i.e. colors that are equally spaced around the color wheel

- Analogous colors, i.e. colors that are adjacent on the color wheel

How to use color themes in Photoshop? Photoshop had a great extension called Adobe Color Themes. You could use Adobe Color Themes to both check the color scheme of your image or you could use it to help you adapt the colors of your image according to a certain color scheme. Unfortunately, since July 2021 the Adobe Color Themes panel is not available anymore, but you can use the Adobe Color web app instead for checking color and for extracting color themes from a photo.

For three of my photos I have shown how the color scheme looks like using the old Adobe Color Themes panel. The first photo has the complementary colors scheme, the second photo has the analogous colors scheme and the third photo has the compound colors scheme. If you want to change the colors of your photo, simply use the standard techniques to change colors in Photoshop or add colors by, e.g., creating a new layer with blend mode ‘soft light’ and use a brush to paint in certain parts of the image with the appropriate color.

And in this way, using these color schemes, you can create images with color combinations that are aesthetically more appealing. However, use these color schemes as a guideline and not as a strict rule. Deviating a bit from this schemes might result in even more appealing images, but be aware that deviating too much might result in color combinations that are perceived as ugly.

So what can you do with the Adobe Color web app? With the Adobe Color web app you can extract a color theme from an image, see below for some examples. After extracting the theme, you can view the colors on the color wheel. In this way you can check the color scheme. In the examples below you can recognize the triadic colors scheme for the photo of Italy and the analogous colors scheme for the forest photo. Using the Adobe Color web app you can also save the extracted color theme such that you can make it available in Photoshop via Libraries, see Window > Libraries in Photoshop.

You can also create a new color scheme based on the extracted color scheme. Of course also this color scheme/theme you can save to make it available via the libraries in Photoshop. Once you have done that, you can use this color theme to change the colors of your photo in Photoshop, if you want. For example, as also explained above, you can change colors by creating a new layer with blend mode ‘soft light’ and use a brush to paint in certain parts of the image with the appropriate color from the color theme. You can also use my actions 'add color' or 'replace color' that are part of my forest workflow. In this case I saved the triadic colors scheme with the name 'Triad extracted' and you can see it in my library. I selected the blue tone of the color theme as foreground color such that I can use it in combination with my 'replace color' action.

Note: for people not so familiar with Photoshop this brief tutorial is maybe overwhelming. Hopefully it gives some insight in the possibilities. In case you want to learn more about this and my actions, please contact me for a workshop.