Actually, I have just solved the issue, haha. I believe it was due to my having selected "Save raw image" in the render viewport rather than "Save color managed image". Thanks again for the awesome script! Also, just FYI, I noticed that if I cancelled a bunch of renders by hitting escape, Maya would often crash at the last frame of the frame range in the script. I'm not sure if that's avoidable, but its something I noticed.