Theoretical studies of color combination and their visual effects find their roots in the works of famous 15th century artists such as Leonardo Da Vinci and Battista Alberti. These artists are among the first to propose the idea that the process of combining different colors can be generalized in a scientific manner. This idea was adapted by Sir Isaac Newton who, in 1666, developed a frequency-based color wheel to show the visual effects of colors on human eyes and the psychophysical results accompanied by them. This work by Sir Isaac Newton ultimately became the foundation of all the advancements in the area of color theory in later centuries.
The basic idea of color theory revolves around the resulting formations of different colors from the mixing of primary (red, yellow and blue), secondary (green, orange and purple) and tertiary (yellow-orange, red-purple, red-orange, blue-purple, yellow-green and blue-green) colors with each other and the involvement of light in their ultimate reflection on the human eye. This involvement of light results in shaping the identity of a color, i.e., warm, cool, achromatic, shaded, etc., which defines its characteristics and identities in different visualizations.
Color theory has standardized many color combinations that are used in different fields of sciences and visual studies in order to bring the elements of harmony and aesthetics within these applications. For instance, it has been noted that the mixing of two primary colors with each other in an equal ratio creates a secondary color; further, the combination of two secondary colors creates a tertiary color when mixed in equal ratios. These combination ratios have been developed with the help of the categorization of colors--an idea originally presented by color theory.
The major aspects of study in color theory include color harmony and context. The term "color harmony" is the aesthetically balanced arrangement or combination of colors so that the human eye has a sense of satisfaction or beauty with it. In this regard, color theory states that any two or more colors adjacent to each other on the color wheel are analogous to each other or can be used in harmony with each other. Similarly, any two colors located at two different positions on a color wheel are complementary, or negative, to each other, and can be used in a harmonious combination. Further, the aspect of color context deals with the collective identity of two or more colors when combined with each other. Color context deals with finding out the visual effect created by the combination of two or more colors. For instance, combining red and green (two complementary colors on the color wheel) reflects a different identity as compared to when green is combined with yellow (two analogous colors on the color wheel).
Color theory has its application in many areas of study and manufacturing sciences. These areas include visual studies, fine arts, architectural design, fashion design, interior or exterior decoration, object identity definition, painting, sculpture design and object modeling. Further, those who use the procedures and theoretical methods of color theory are typically artists, decorators, designers and scientists; these professions require fundamental color harmony and context principles to give certain objects their true aesthetic identity.