Iphone masking colors: Remove background color

Question

Hi,

I have a series of avatars; each has a hot pink background of RGB:255,0,255.

Rather than going through every avatar, and manually removing the pink background; is there a way to make Objective C remove the background (masking it) for me?

An example of an avatar follows:

One thing I am concerned about is that the masking is done on the fly, and may cost memory; is this something I should be concerned about?

Additionally, let's say I put the avatars in a spritesheet; could I apply the mask once and work with that?

Thanks for your help.

Answer 1

If you added the buttons programatically you could set a global NSArray and addObject:yourButton each time you make an avatar button, then when you want to remove the background do this:

for (UIButton *custom in globalButtonArray) {
    custom.backgroundColor = [UIColor clearColor];
}

Answer 2

see function CGImageCreateWithMaskingColors. I think this is what you need. See reference: Masking an Image With Color