Use it to convert an image to a JASC 256-color palette. You can feed it all common image formats: bitmap, png, gif, jpeg, etc
The image you supply has to be 16x16 and be pixel-precise. So I would advise against using anything other than bitmap/png for best accuracy. Each pixel is taken as an individual color for the palette. The color layout of the palette-sketch will be preserved.
Run it with the win cmd: bmp2jascpal -in <input> -out <output> where input is the input palette-sketch image & output is the .pal file that will be generated.