Back to the information page
About algorithmic worldsIntroduction
The piling operator
Before seeing how an algorithm can produce a picture, let us recall how images can be encoded digitally.
A television or computer screen is composed of a large number of "pixels", points able to display a color. Similarly, a digital picture consists of a set of points forming a square lattice, each of them being assigned a definite color. If the number of pixels is large enough, the eye has the illusion of a continuous image. As the human eye contains only three types of cells sensitive to color, any visible color can be decomposed into three channels, three "primary" colors, which correspond roughly to red, green and blue. Therefore, a pixel of a screen is physically composed of three light sources emitting red, green and blue light and whose intensity can be varied independently. The color of a pixel can then be encoded by three numbers describing the intensities of the primary colors required to produce the color. From this point of view, a digital image is nothing but a collection of triplets of numbers, specifying the color of each pixel. The resolution of a digital image is the number of pixel it is made of. (Warning, when it comes to printing, this term has a slightly different meaning...)
This digitalization of the notion of image allows us to imagine how an
algorithm may produce pictures. After performing computations and
logical operations on the initial data, a pictorial algorithm must
return a triplet of numbers for each pixel of the digital image.