How is a negative image figured out?

Question

My program im working on does grayscale, builds an alpha mask, and splits the color channels. How do you invert a picture?

the above are done looking at the image pixel by pixel.

Im using vb2005.net, for the sake of speed is there other ways of doing those things using drawing.graphics?

Answer 1

See this. You'll basically have to use either ColorMatrix:

new float[][]
{
   new float[] {-1, 0, 0, 0, 0},
   new float[] {0, -1, 0, 0, 0},
   new float[] {0, 0, -1, 0, 0},
   new float[] {0, 0, 0, 1, 0},
   new float[] {1, 1, 1, 0, 1}
}

or unsafe processing (not sure if this particular one can be done in VB.NET)