Polygon Graphics without edge feathering

Question

If you look closely at the colors used with a simple polygon graphic in Mathematica, they feather the colors at the edge to make for a nicer graphic, but I don't want that for my project. I want to control the number of total colors that will be used in the exported bitmap. How can I create a graphic of multiple different colored solid polygons and end with a final result that has that exact number of colors. For example:

image=Graphics[{Red, Triangle[{{0, 0}, {1, 0}, {0, 1}}], 
  Blue, Triangle[{{1, 0}, {2, 0}, {2, 1}}], 
  Green, Triangle[{{2, 1}, {2, 2}, {1, 2}}], 
  Yellow, Triangle[{{1, 2}, {0, 2}, {0, 1}}]}]

If you analyze the output from ImageData[image] you can see shades of red, green, blue and yellow are used on the edges. Exporting this to a bitmap creates a file with many colors. I want to export this to a bitmap with exactly 5 colors: white, red, blue, green and yellow. I have played with EdgeForm with no luck. Thanks!

Answer 1

You can use the Antialiasing option to get what you want:

image = Graphics[
  {
   Red, Triangle[{{0, 0}, {1, 0}, {0, 1}}],
   Blue, Triangle[{{1, 0}, {2, 0}, {2, 1}}],
   Green, Triangle[{{2, 1}, {2, 2}, {1, 2}}],
   Yellow, Triangle[{{1, 2}, {0, 2}, {0, 1}}]
   },
  BaseStyle -> Antialiasing -> False
  ]

Rasterize@image