Image processing is fun! Usually computers can't understand images as well as we do, but they are getting close. What is an image? A computer thinks an image is a 2-Dimensional array of picture elements ( pixels ). Each pixel can be a color, a gray value, or a binary image (like those used in our thermal printer tutorial ). In a binary image each pixel is just a one or a zero, black or white, on or off. In a gray scale image each pixel is a number indicating the distance to black or white, commonly 0 is black and 255 is white. A full color image is usually understood in terms of it's color channels: red, green, and blue or hue, saturation, and brightness . Why is color 3D? Remember a gray scale image just needed one number to represent it, but a color typically requires three. Why?! Check out some nice java-based image-processing tutorials at image processing basics .