Imagine you have a panorama photo, stitched together from multiple pics, and it's already been merged into one JPEG. Each pic had a slightly different brightness/color/tone. So you can see obvious lines between the stitched images where the colors don't match.
Is there a way to correct this semi-automatically, in any version of photoshop? Other programs welcome too.
This pic might illustrate it better. The quarter itself is ok, but the white area to the right, the black area near the bottom, and the wood platform at the bottom right all feature these rectangular mismatched color areas.
Am I stuck selecting each rectangular area manually and then lightening/darkening it by eye?