Edge blending of image with alpha on iOS after masking color

Question

I have an image that has been masked with a range of colors using

CGImageCreateWithMaskingColors()

Everything works fine, but the edge of the image (we are using a green screen for profile pictures) is pixelated. I've tried drawing the image in an image context and a bitmap context with the proper antialiasing, but the edges remain the same.

Any suggestions on how to smooth the sides of the profile after it has been masked?

Answer 1

You could try zooming the mask image larger by some multiple (say 2X, 3X or 4X) before creating the mask. Then a size-reduced copy of this larger mask might be better antialiased.