Blitz uses 5 different graphic formats:
c16 16bit color. 5bit red, 5bit green, 5bit blue, 1bit alpha. rrrrrggg ggbbbbba
- used when you have over 256 colors in an image
ci8 indexed image, up to 256 colors in the palette. Indices are 8bit, and palette is c16.
- Used when you have 256 colors or less.
ci4 indexed image, up to 16 colors. Indices are 4bit, so two per byte. Palette is c16.
-Used when you have 16 colors or less
The following ones I don't see you using to often:
i4 4bit greyscale image. Each nibble is a seperate pixel. Note in-game this is treated as a two-tone image, and they can colorize the "white" and "black" to any color--even transparency.
ia8 intensity+alpha. Upper nibble is the grey, lower nibble the alpha.
Other things to make note of:
*The team's numbers, socks, and stripes can only have a four-color palette (3+1 transparency), where socks and stripes use the same palette.
*Jerseys can only use 12 colors (11+1 transparent).