I have just learned that PNG is a lossless image format while BMP can be both uncompressed or lossless format. Should there be a quality difference between these two? If not, does it mean that other lossless formats like TIFF, JPEG2000 and PNG offer the same quality as BMP?

  • 5
    JPEG2000 is not always lossless. You can use it lossless, but mostly, it's used to compress images in a lossy way. – slhck Feb 4 '12 at 22:10
up vote 13 down vote accepted

BMP is both uncompressed and lossless. PNG is compressed but lossless. Thus, with a lossless format the only visible difference is the file size. I'd recommend using PNG over BMP unless you can't for compatibility reasons.

  • 1
    You said visible difference. Should there really be any difference except for file size? – user1032421 Feb 4 '12 at 22:13
  • 3
    That is correct. The pixels will be 1:1. – iglvzx Feb 4 '12 at 22:15
  • 1
    PNG also supports transparency while BMP doesn't. – dnbrv Feb 5 '12 at 4:05
  • 5
    BMP does support alpha channel (transparency) since Windows 95. Just that Paint in Windows does not save the file with transparency (for compatibility reason?), which I think might have been the source of misconception. – nhahtdh Apr 6 '13 at 21:59

There's no quality difference between BMP & PNG format (except PNG is compressed using deflate algorithm).

BMP8 can be compressed using RLE (run-length-encoding) algorithm, but BMP16/24/32/64 doesn't support compression yet.

BMP32 support alpha channel just like PNG32 support transparency.

No difference in quality, both standards are lossless. BMP uncompressed takes more space, but when compressed (e.g. when put in a .zip or .7z file) BMP can be better.

Having done some experiments, I saved a photo in BMP and in PNG, and compressed both files. (.zip) The BMP was 1.8% bigger, but that would vary between photos.

If you are compressing photos, it makes no difference.

However simple picture, such as a drawing you did in paint, or a diagram, will compress much better with .bmp rather than .png.

I again, tested this. I did a logo in paint (similar to a ford logo) and compressed it with 7zip. Uncompressed, the png was 136kb, the bmp 1.7 MB. Compressed, the png was ~100kb and the bmp was 18kb.

If you want to compress pictures, save in .bmp. If not, use .png.

Both when compressed whooped jpeg btw.

Your Answer

 

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.