Quoted from oga83:This is a good hint !
As the images are 4-bit encoded, you can use a 16 level palette.
Although I did not test it, the one below should give good results (low nibble is just ignored to convert each color to 4-bit)
0,0,0
16,16,16
32,32,32
48,48,48
64,64,64
80,80,80
96,96,96
112,112,112
128,128,128
144,144,144
160,160,160
176,176,176
192,192,192
208,208,208
224,224,224
240,240,240
Quoted from Russo121:GIMP 2.8 for image editing (free. Laid out like photoshop)
http://www.gimp.org/
I have downloaded gimp and cannot figure out how to load or setup the palette as suggested. Can anyone help out with a tutorial for dummies (me). thx.