I've talked about looking for color opportunities in your paintings in passing before but people ask me how do you go about seeing more color? Like everything else color sensitivity can be acquired with focus and practice. The best way to learn about color is to paint directly from life outdoors. While working indoors is better than working from photos, it is still constricted to the variety nature has to offer.
an example of manipulating hues
The intensity of the light and its direction, the quality of the atmosphere outside provide so many more choices for your paintings than any other way of working. In fact there are so many choices outdoor work forces them to be made and it informs us about relationships of colors we could never calculate in the studio on our own. By focusing your attention on color and color relationships outdoors you will become more sensitive toward seeing colors.
an example of manipulating chroma and hue
For you to introduce color opportunities into your work the structure of the painting must be well grounded. To do this you must prioritize the aspects of color for each image you paint. Be aware that colors and their aspects are not isolated but that they interact with everything else in the scene. The success of your color depends on your ability to recognize what you see and translate the essence of that experience, filtering out the unnecessary or unimportant. This is where designing the idea of the painting helps you. Design is imposing structure and limitations on what you see to create a more powerful statement than just strict mimesis would allow. By consciously deciding what approach is best for a particular subject you improve its impact.
an example of manipulating values
The aspects of color you have at your disposal are Value, Hue and Chroma. If you understand this you can decide which aspect dominates the scene you are looking at. This is where the decision process allows color choices to be made and insures your choices are unique to your way of thinking. If you decide the values need to be maintained then the opportunities for color are with your hues or chroma; if the hues or chroma are being maintained then the opportunities are with values. In my opinion a good painter reveals their process of seeing the world through these decisions. Outdoor work gives you the largest possible set of combinations and relationships to pick from and prioritize with and that is why field work is important and must be continued throughout a career.