Windows' original uncompressed image format — simple, huge, and still generated by some legacy software and screenshot tools.
BMP (Bitmap Image File) is the image format Microsoft built into Windows from its earliest versions, storing each pixel's color value with little to no compression. That simplicity made BMP easy for early software to read and write reliably, which is exactly why decades-old Windows applications, some scientific and industrial software, and certain screenshot or screen-capture tools still default to it. The tradeoff is size: an uncompressed BMP of a photo can be several times larger than the same image saved as JPEG or PNG, with no corresponding gain in quality once the source is a normal photograph rather than sharp-edged graphics or line art. Outside of Windows-native and legacy software, BMP support is thinner than it once was — many web platforms will not accept a BMP upload, and it is not a practical format for email or messaging given how large the files run. A BMP that shows up from an older program or a Windows machine usually just needs converting into something smaller before it can be shared or posted anywhere.
iPhone, iPad, and Mac open BMP natively in Photos and Preview. Windows displays it natively, as expected given BMP's origin. Most web browsers can display a BMP directly, but many upload forms and messaging apps reject the format or the large file size that comes with it.
A BMP file's size makes it impractical to email, message, or upload to most modern sites, and a growing number of platforms reject the format outright. Converting to JPEG or PNG on-device shrinks it down without needing the Windows software that produced it in the first place.
Filemorph can convert BMP to JPG on-device — a small fraction of the file size with no visible difference for an ordinary photo.
Filemorph converts .bmp files entirely on-device on iPhone, iPad and Mac — no upload, no account, and it works in Airplane Mode.
Relevant operations in Filemorph:
BMP stores pixel data with little or no compression by default, so a photo saved as BMP can be several times the size of the same photo saved as JPEG, with no visible quality advantage for an ordinary photograph.
Older Windows software, some scientific and industrial imaging tools, and certain screen-capture utilities still save images as BMP by default, since the format has been built into Windows since its earliest versions.
Yes. Filemorph converts BMP files entirely on-device, so an old screenshot or a file from legacy software never has to be uploaded anywhere to shrink it down, and the conversion works with no internet connection.