What is causing this?

[pookers]

Recently I've been getting these weird pixelated colored spots in my photographs. I'm not sure if it is caused by post processing (I use a plug-in for GIMP), or my camera Canon Rebel T1-i. I don't think it happened before, so I think it is a settings or a post processing effect that is causing it. Any ideas? I shoot in RAW and most of the affected pictures were taken with flash indoors, but the first one was not taken with flash. I found that if I changed the pictures to black and white or sephia the pixels blended back in. The first one there is weird green pixelation under her chin and pink pixelation on her blue shirt. The second one the pixelation is particularly bad on her shirt.

 

[Derrel]

" It's a feature, not a bug." (quote attributed originally to Microsoft, now used by Canon)

On the second shot, it looks like perhaps the camera's demosaicing routine guessed incorrectly on what color the pixels needed to be...a digital camera with a bayer array of red green and blue pixels basically has to "reconstruct" the colors from the red,green,and blue mosaic pattern...sometimes the routine isn't as good as it should be...this falls under the heading of what author and photojournalist Rob Galbraith used to call "Digital Weirdness". A few years ago, digital weirdness was much,much more prevalent than it is today, and yet, there are still some subjects, and some situations, that give digital capture systems problems in rendering real-world objects properly.