Practical color photography wasn’t available until 1907. Until then, we lived in a black and white photographic world. The use of color in photography changed everything and while many photographers study composition, posing, gear and lighting, not enough study color.
Color can accomplish many things in a photograph. It can set a mood, draw attention to a subject, convey a story even. Knowing that color works in these ways can help photographers plan their shots more effectively.
Start by looking at your scene’s natural color palette. What are the dominant colors? What are the supporting colors? One way to do this is to shut your eyes and squint at the scene so that detail is minimized and the colors show through.
In your mind’s eye, separate the colors that are dominant. Then think of colors in the scene that may compliment the dominant color. Ask yourself what mood you want to set using these colors. For instance, warm colors are often used when you want to convey sensitivity or safety. Cool colors are are more in your face and more businesslike. Ask yourself which message you want to send and compose your image with the colors that express the relationships, mood and impact you want the viewer to see.
There are all sorts of subordinate color relationships you can explore. Some examples are monochromatic, analogous, and complimentary.
So while you may think of color as something that just “happens” in a photo, it can be much more. It can be a strong compositional element in your image.
Way back in 1810 a man named Johann Wolfgang von Goethe published a book called “Theory of Colours.” In this book, he assigns a value to each color. Those assignments are Yellow = 9 Orange = 8 Red = 6 Green = 6 Blue = 4 Violet = 3. According to his theory, picking colors in accordance to their intensity (yellow being most intense at 9) helps you create harmony. A color that has 50% more intensity than another should be subordinate to the less intense color.
Does this leave you scratching your head? It did me. I have read all the material on this I can. You can start at Wikipedia – and I suggest you dig deeper if interested. Whether you agree with it or not or even understand it is less important than my real goal. I want you to see there is so much more to color than it just being there. Use it.