I made a few optimizations, fixed bugs and added a color palette browser to the bitmap viewer. The colors are located at 0x669234 until 0x66A0A0 in the HF10 FW and are each one word long in the format 0xRRGGBBAA... I'm not completely sure about the alpha channel though and I also couldn't find out how the colors are mapped to the bitmap values, but that's not important anyway.
I couldn't find the color table in the HV30 FW but I only took a quick look.
I think I also found out what the second byte in the bitmap header is... it is probably the width that the bitmap gets stretched to when being displayed.
Speaking of bitmaps, I also found another type of bitmap in the HV30 FW... its header is 4 bytes long, each 2 bytes being width and height. they can be found at the following offsets in the file:
from 35441A to ?? (a few ones) 1byte align
35E30A
357FAC - 3A917F 1byte align (includes e.g. the transition effects animations)
There are probably a few more, unfortunately it's not one continuous section.
If you want to look at those set the alignment to 1 and uncheck "symbols" ("symbols" means 2 byte header that's used for fonts/icons).
I couldn't find similar bitmaps in the HF10 FW although they must be somewhere... maybe they're compressed.
