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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?

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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 9 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.

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You said visible difference. Should there really be any difference except for file size? – user1032421 Feb 4 '12 at 22:13
That is correct. The pixels will be 1:1. – iglvzx Feb 4 '12 at 22:15
PNG also supports transparency while BMP doesn't. – dnbrv Feb 5 '12 at 4:05
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.

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