Image Processing:

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:

• The true color, or RGB, in which the 3 color components are stored (that is red, green, & blue, in that order).
• Index into a colormap: the value stored is an integer which refers to a row in a matrix known as colormap. The colormap stores the red, green, & blue components in three individual columns.

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

    etc.