Alley in Pisa, Italy

by Lars Kotthoff

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Which image compression is better, LZW or ZIP? I am using Lightroom to export images.

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Just in case there was any doubt: Both LZW and ZIP are lossless compression, so there's no degradation of image quality with either. The "best" algorithm will pretty much be whichever one produces smaller files, although there could also be compatibility issues with older software, as John Cavan mentioned in his response. –  coneslayer Apr 14 '11 at 1:44
    
I'd suggest you test with a typical subset of your own images. LZW+Prediction gives smaller results with my typical 24bit-pictures and software ... but you use something different. –  Leonidas Apr 14 '11 at 14:04
    
To "what is better" the answer is always: "Yes". –  his Jan 29 at 23:23
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3 Answers 3

up vote 9 down vote accepted

Better is a relative term and, to some degree, will vary in terms of amount between the two depending on a variety of factors including the bit-depth, frequency of discrete colours, etc. Some experimentation may be necessary on this front, though my reading indicates LZW is good for lower bit-depth images with lots of the same colours and tones in it and ZIP for when that is not the case. In other words, if the image is 8 bits go LZW and if it is 16 bits go with ZIP, as a rule of thumb, but with the caveat that it's not an absolute rule and there may be exceptions.

The only other thing I'd note is that LZW has been in the TIFF standard since 1992 and ZIP since 2002 (as part of a supplement when Adobe added it). While that's probably more than enough time for it to no longer be an issue, there may be the odd piece of software out there that handles LZW compression but not ZIP.

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I recommend LZW for when you want to flatten the image to use in a catalog or for print. It is a great lossless file type, if Only Adobe can make their file size smaller. Anyway, hope this helps. :-)

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Why do you recommend this? –  damned truths Feb 15 '13 at 5:17
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If the image is line art with large flat colours then LWZ compression, which is run-length encoding(RLE), will work best.

If you have a photographic image, I think ZIP will give better compression.

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LWZ is not RLE. marknelson.us/1989/10/01/lzw-data-compression –  mattdm Apr 14 '11 at 0:20
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