Learning to Draw: Chapter 4

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Index of Chapter 4 - Lights, Shadows and Colors

1. The Light and the Human Eye
2. A Choice of Colors
3. Painting Technics

Chapter 4 - Lights, Shadows and Colors

Most of the "realism" of a picture is based on a good light and shadow representation.

Again, there are two ways to practice light and shadow drawing: observation and study. The study of light and shadow is very similar to the perspective drawing study:

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4.1 - The Light and the Human Eye

The human eye is a complex optical device, composed by lens, muscles, blood vessels and sensors. By now, only the sensorial components are relevant.
There're basically two kinds of light sensors in the eye. One kind is very sensible to light, but cannot recognize colors. The other kind, less sensible, can recognize three light spectrum bands:

Some color sensors can detect a red band, others a green band and others yet a blue band. These are called "primary light colors". When a human eye receives light with an intermediary color, the sensors are partially stimulated and the brain associates this partial stimulation with a psychological color. If two light sources, each with one primary color, are turned on with the appropriate intensity, the brain will "see" the same psychological color:

Using just three light sources, each with one primary light color, it's possible to "show" to the brain all light spectrum colors:

Note that the combination of red and blue light results a color that doesn't exist in the light spectrum, the magenta. The yellow, cyan and the magenta are called secondary light colors.

Another important point that must be explained is that light colors are "additive", what means that each light component you add will increase the brightness of the colors:

When working with a computer, you deal with primary light colors, but when using paints, the rules are "inverted", because they are "subtractive". If a white light passes through a red paint, for example, it is "filtered", i.e., it becomes darker. The "primary paint colors" are the yellow, the cyan and the magenta, exactly the secondary light colors. Mixing primary paint colors results the secondary paint colors:

4.2 - A Choice of Colors

The perspective drawing provides great realism to a picture, but not all pictures allow good use of it. An example:

The object at the left is larger than the one at the right, but they are represented the same size when in perspective. The human eye, and other optical devices, have a focus. Objects at the focal distance appear very "well defined", while objects out of the focal distance appear "blurred":

Objects more distant from the focus appear more blurred then the nearest ones, don't matter if the object is close or faraway to the viewer. Drawing blurred objects can solve the problem of the perspective:

The amount of "blurring" depends on the distance to the focus:

And how to do this "blurring"? This depends mainly on the medium you are working. In B&W (Black and White) pictures (black ink pictures, for example), the blurred objects have their border lines "less sharp":

In gray scale pictures (pencil drawings, for example), the blurred objects have their borders "lighter":

In color pictures, the blurred objects have their colors mixed:

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Painting Technics

Page last modified on 1997-April-9 Wednesday.

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