Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
The color reduction algorithm has been improved since the 6.2.4-5 release which can account for the difference you see. Using the compare utility we see a normalized MAE of 0.000191543 and the difference image suggests slight changes around the letter edges. Given these slight color difference, what makes the current algorithm "wrong".
Hum... right.
I see that in fact it isn't generating a "wrong" palette (it just changed the way of generating it). But is it a way to have the old one generated (or something similar), please?
Unless you can show that the current color reduction algorithm has a bug, our only suggestion would be to use an older version of ImageMagick to reproduce the original output image. Color reduction is a fuzzy process, meaning different algorithms can produce different results but still be correct in their behavior.
