Reading: none
Images are typically stored as a set of pixels. Each pixel represents the color of a specific dot of the image. Loading a standard image into MATLAB is easy, for example loading the image above into MATLAB is done with:
image = imread('slu.png');
The slu.png image has 600 pixel rows and 800 pixel columns, so the above command generates a three-dimensional matrix of size 600x400x3. (Each pixel is stored with a red, green, and blue channel, so the third dimension is 3.) For example, the command:
image(123,234,3)
accesses the blue channel of the pixel in the 123rd row of the picture and the 234th column of the picture.
Image Convolution on Wikipedia