Direct edit if palette entry in PNG?

[SvenBent]

i have made a B/W picture into a png file and optimized it with ~800 iterations of pngout).
the png file is 1bit palette entry

however now i can se that the palette entry is wrong. the black is only 11,11,11 (decimal) and not 00,00,00

i now wish to just edit the palette value without losing the optimized compression.

is there a tool for that or do i need to run my 800 iterations again ?

the reason i wnat to change is because i want to run another 200 iterations with 1bit grayscale instead of 1bit palette to see if it improves compression

[chornobyl]

tweakpng
http://entropymine.com/jason/tweakpng/

[SvenBent]

Thanks this worked awesome.
going to keep this treasure