I'm trying to save a 4 bit .bmp, but the only way I can get the "4 bit" option so that it's not grayed out is if I use "force black and white" in the indexing options. If I don't use "force black and white," the color table is generated as expected (and desired), but then the only option I have upon saving is "8 bit." As soon as I go back and re-index with "force black and white" selected, then I get the option to save as a 4 bit .bmp.

I am not aware of the .bmp format having a requirement that a 4 bit version must have black and white in the palette. Does anyone know why Photoshop CS2 wants to force this? And is there some way around it?