Hehe.. could be. Actually, there is an issue with P4 .bum files, but to correct that problem you have to first create the .bum file (black = low, white = high), then load the .bum file into your paint program, split it into red green and blue channels, invert the green channel only, recombine the channels and re-save it. There's older threads on this topic, but I don't have links handy.

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