Graphics Programming with GDI+

10.7. Color Transformation and the Color Matrix

So far we have seen the transformation of graphics shapes from one state to another, but have you ever thought about transforming colors? Why would you want to transform an image’s colors? Suppose you wanted to provide grayscale effects, or needed to adjust the contrast, brightness, or even “redness” of an image. For example, images retrieved from video and still cameras often need correction. In these cases, a color matrix is very useful.

As we discussed in earlier chapters, the color of each pixel of a GDI+ image or bitmap is represented by a 32-bit number, of which 8 bits each are used for the red, green, blue, and alpha components. Each of the four components is a number from 0 to 255. For ...