4B data size DS
4B offset to pixels
32B zeros
4B description string offset DSO
attributes {
  2B width - must be increased to multiple of 2 if odd
  2B height
  1B 0x01
  1B bits per pixel:
      -0: 4bit
      -1: 8bit
  1B subtype:
     -3 RGBA
     -4 greyscale
     -5 ? ov_rdir
  1B 0, 0x80/128
}
4B zeros
4B ?
xB pixels
(DSO - DS)B description string (zero term.)

if there's more data in file, repeat


subtype:
0 - palette 16x3B RGB, 4bit per pixel
1 - ?256x4B palette RGBA, 8bit per pixel?
2 - ?16bit RGB?
3 - RGBA 32bit
4 - grayscale, 4bit per pixel if bpp = 0, else grayscale 8 bit
5 - grayscale, 16bit per pixel