I have a bunch of images that have been converted into .png format, and I need to set their alpha layers so that pixels of a certain color are transparent. Unfortunately, I can't find a way to set pixels of one exact color to be transparent. I need all pure-pink (ff00ff) pixels to be set to fully transparent, and have all other pixels be fully opaque. Is there some way to do this? Thanks.

In gimp you can select by color, choose a pixel with ff00ff and turn the tolerance all the way down. Then delete the selection and save the image.

You are too helpful for your own good. Thanks!