This is the minimal bit-depth needed to fit the full 9-bit Atari ST, MSX and the full Amiga (HAM) color palette.
The 16-bit indexed png is unofficial, but exists.
For the transparency matter, unless u can have 2 blacks, which of only 1 is transparent, only ARGB4444 bmp is the only one that carries transparency. (I forgot to mention in #45 PNG has tRNS, I wonder if you used that, for .gif it is also customisable I checked).
This is also similar to my TGA request #16, I care more about bmp/png than tga.
This is the minimal bit-depth needed to fit the full 9-bit Atari ST, MSX and the full Amiga (HAM) color palette.
The 16-bit indexed png is unofficial, but exists.
For the transparency matter, unless u can have 2 blacks, which of only 1 is transparent, only ARGB4444 bmp is the only one that carries transparency. (I forgot to mention in #45 PNG has tRNS, I wonder if you used that, for .gif it is also customisable I checked).
This is also similar to my TGA request #16, I care more about bmp/png than tga.