The Images are represented as grids, or matrices, of picture elements (known as pixels). In MATLAB an image usually is represented as a matrix in which each and every element corresponds to a pixel in the image. Each element which represents a particular pixel stores the color for that pixel. There are two basic ways by which the color can be represented:
For an image which has m × n pixels, the true color matrix would be a 3-dimensional matrix with the size m × n × 3. The first two dimensions show the coordinates of pixel. The third index is the color component; (:,:,1) is red, (:,:,2) is green, and (:,:,3) is the blue component.
The indexed presentation rather would be an m × n matrix of integers, all of which is an index into a colormap matrix which has the size p × 3 (where p is the number of colors available in that specific colormap).Each row in the colormap has three numbers presenting one color: first the red, then green, and then blue components. The illustration is as follows,
[1 0 0] is red
[0 1 0] is green
[0 0 1] is blue