BMP and TIFF: high-quality image formats
Uncompressed quality
BMP and TIFF are formats designed to store image data without lossy compression. They are often used for scanned documents, archiving, and image processing, where every pixel matters.
The cost is file size. A BMP or TIFF can be many times larger than the same image saved as JPG, which makes the originals awkward to email or upload.
Converting for everyday use
Convert BMP or TIFF to JPG for photos that will be shared or uploaded: the file shrinks dramatically with barely visible quality loss. Convert to PNG when you need lossless quality in a more compatible format.
For archival copies, keep the original TIFF. The converted JPG or PNG is a working copy, not a replacement for the master scan.