1) "local" or object color (e.g. the apple is red, the banana is yellow)
2) light source color (e.g. firelight is reddish, ambient skylight is blue)
3) global colorization (the whole picture is influenced by a single tonal center; there is no direct real world corollary for this, but it's similar to the effect of atmospheric perspective (haze, colored smoke, etc.) but without the reduction in contrast that occurs in those natural phenomena).
Each of these is rooted in real world visual principles, which our eyes and minds have been trained to decode. Our visual apparatus has evolved to automatically adjust for and filter out many of the things artists are most concerned with creating, and it takes a lot of training to be able to see objectively and subjectively at the same time.
Local (object) color connections only
These are not rules to apply when making a painting, but rather principles of perception to understand when assessing your paintings. That is, these are connections the eye naturally looks for, and finds. If parts of the painting are connected in one way, but other parts are not, the paintings colors can unintentionally become disjointed. This about learning to see these connections and exploit them, and/or correct colors that aren't working.
Light source colors overwhelm local (object) colors
This is not a full exploration of the use of color in a painting or of how light works - light does a lot more than this! These are just the three broadest types of connections we tend to look for in painting. Understanding them can really help you get a handle on your color work and identify problems, especially when you are not working from life or any reference.
All colors strongly influenced by a single color
The diagrams here are just that - diagrams. They are not meant to look "real" as they ignore many important areas of color perception and color in painting (for example, reflected light, variation of light within lit and ambient areas, specular "highlights", occluded areas not reached by any light, etc.).
For discussion, relative to this chart we can think of these as "horizontal" (the horizontal bands of local color on the block), "vertical" (the vertical division between the lit and unlit sides of the block, and the resulting vertical continuity within each side) and "global", respectively.
Three types of continuity, overlapping
Sometimes artists think "horizontally", that is, local colors dominate, light colors are underplayed or non-existent (light is white, shadows are black), and no overall colorization is considered. This is where most picture makers start off. If colors are not too saturated, they don't clash, and appear to work ok:
Local continuity only, but low saturation
This is where almost everyone starts (and many people stay). The middle stripe is red, the bottom stripe is yellow, etc. The color of the dark, "shaded" side of an object is simply a different "version" of the lit color (or both are different versions of some neutral object color without respect to any light source, as if such a thing could exist...). Usually shadows are thought of as black(er versions of the object color). Some teachers refer to this approach as "chromophobia."
Other times artists think more "vertically", that is, light colors strongly influence the apparent colors of the objects, though each stripe still reads quite clearly as green, red, black, etc.
Light source color is emphasized but doesn't overwhelm local colors
This approach considers the lit and unlit areas of elements as different versions of the main light and ambient light (or shadow color). Pictures like this can look "dichromatic" (made from two colors), especially when there is a single strong main light and a single strong ambient light, as in bright daylight.
Note that there is no inherent connection in the physical world between the color of a light and the color of "its" shadow (e.g. "warm light, cool shadows"). In fact, by definition a shadow is an area not touched by the light in question. Making paintings with warm light and cool shadows (or vice versa) is of course, just fine, though. Distinguishing light and shadow by temperature variation can be very effective.
Many artists employ strong colorization to tie an image together. The image is overall reddish, but local (object) color distinction is still apparent:
This is one way in which color can be used for purely expressive or symbolic value, but also to create a limited palette, wherein a given color can appear as another color, which is visually gratifying in a way that is difficult to explain. It's sort of like... the painting truly becomes an alternate, though complete, reality.
There is, however, a big difference between a painting that is truly monochromatic (check out Mark Tansey's work) vs. one that is heavily influenced by a strong tonal center, but still appears to show variation in temperature, saturation and hue.
A true monochrome image
Strong tonal center but not monochrome
In Part Two we'll see how to identify the different types of connections in your own paintings, and, most importantly, to troubleshoot for disconnected colors. We'll also explore another form of vertical color organization.