To artists, a line is a powerful geometric entity, whether it’s a straight or curved mark on a piece of paper. According to the author on neurobiology Carl Schoonover, the drawing by Picasso at left shows that we can distinguish shapes easily with a few lines, which he says “taps into our visual system's predilection for line.”
Yesterday I started to pose a few questions: Are lines merely abstract constructions—artificial conventions—that we have invented to represent nature? Do they have counterparts in the real world and in our minds? Do they reflect something basic going on in our brain when we look at the world?
These can be sensitive questions for artists who do most of their work in line. They are often made to feel that what they do is just a preliminary step, or that it isn’t as advanced as what a painter does. In fact, the management of line is one of the most sophisticated skills an artist can master, and it corresponds to some of the most basic and powerful experiences of visual perception.
We use lines to describe several things:
1. A boundary of a form (B, above).
2. An edge of a surface marking (A).
3. A plane change within a form (C).
4. Or an edge of a cast shadow (D).
5. Also, a line can describe a thin form, like a tree branch or a piece of spaghetti.
A shape boundary can be regarded as a type of line. Some images, like this poster by Maxfield Parrish, can be made up entirely of overlapping shapes.
At the initial level of visual processing, neuron groups in the visual cortex begin to process shape boundaries in a similar way that they process outlines drawn on white paper. But as we'll see in later posts, edge detection is just one preliminary step in object recognition. The brain constructs an understanding of shape and form and space by combining information from many different cues.
Our visual system has no trouble sorting out boundaries, surface marks, plane changes, and cast shadows (click to enlarge). But they are not trivial tasks when you’re trying to educate a computer, even a smart computer, to see. Edge detection and feature extraction are exciting frontiers for people at the intersection of computer science and visual perception.
That last photo is from Wikipedia on Edge Detection
Colored cube is from GurneyJourney "Color Constancy Illusion" post.
Lines and the Brain Series,