BMP converter
BMP files are big, plain and easy to decode, which makes them the easiest format on this site to convert perfectly: the pixels are read exactly and repacked. Decoding happens in your browser, so even that 80MB legacy scan never gets uploaded.
What is BMP?
BMP is the Windows bitmap format from 1987: pixels stored essentially raw, usually with no compression at all. Ancient tooling, scanners, screenshots from legacy systems and some scientific software still emit it, and almost everything can read it, but the files are enormous for what they contain. Converting a BMP loses nothing, because there was never any lossy compression inside to begin with.