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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?
user1032421
Posted 2012-02-04T21:56:43.433
Reputation: 227
15
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.
iglvzx
Posted 2012-02-04T21:56:43.433
Reputation: 21 611
1You said visible difference. Should there really be any difference except for file size? – user1032421 – 2012-02-04T22:13:14.210
3That is correct. The pixels will be 1:1. – iglvzx – 2012-02-04T22:15:28.607
1PNG also supports transparency while BMP doesn't. – dnbrv – 2012-02-05T04:05:36.747
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 – 2013-04-06T21:59:31.9637
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.
Tidy Star
Posted 2012-02-04T21:56:43.433
Reputation: 71
1
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.
BristolBrick
Posted 2012-02-04T21:56:43.433
Reputation: 21
5JPEG2000 is not always lossless. You can use it lossless, but mostly, it's used to compress images in a lossy way. – slhck – 2012-02-04T22:10:00.597