Remove Hidden Data From BMP Images
11 The oldest, plainest format on this list
BMP dates to early Windows and, in its most common form, stores pixels completely uncompressed - which is exactly why BMP files are so much larger than an equivalent JPEG or PNG. Because there's essentially no metadata standard built into BMP the way EXIF is built into JPEG, camera-style metadata (GPS, camera model) almost never shows up here. Most BMP files you'll actually encounter today come from screenshot tools, older Windows software, icon/cursor editors, or as an intermediate format other programs write before converting to something smaller - not from a camera or a phone.
Go deeper: what "hidden data" even means in a format with no metadata standard
BMP's header declares exactly how big the pixel data is - so, the same as every other container format on this site, anything appended after that declared size is extra data that a normal viewer never shows you but that's still physically present in the file. Full pixel reconstruction removes it unconditionally, the same guarantee described on the comparison page, whether that trailing data is metadata, a polyglot payload, or just leftover junk from whatever tool last touched the file.
Why you'll more often end up with a BMP than start with one
BMP shows up as an output option here mostly for compatibility with older software that expects it, rather than as something worth choosing for a new file - PNG gives you the same lossless quality at a fraction of the size. If you're not sure which to pick, PNG is almost always the better choice unless something specific requires BMP.