Just 'cause I'm curious, are you saying every bitmap format aligns each line of pixels to 4 bytes?
The problem I fear is that bitmaps do use padding (4 bytes per line), so that probably won't work.
Or that, regardless of the length of a line, there are 4 empty bytes at the end of each one?
And is the first bit or the last bit of a 16-bit 555 bitmap pixel the ignored bit?
Not every bitmap format, only the Windows BMP format AFAIK.
Every line of pixels is padded to a full multiple of four bytes. The padding bytes are added at the end of a line. 16-bit bitmaps are always stored as 5-5-5, xRRRRRGGGGGBBBBB, unless the color masks in the header say otherwise. For simplicity sake the color masks in the sample hex dump are set to 0, then xRRRRRGGGGGBBBBB is the default.