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Undo LZW compression
Hi Y’all
Is there any way to undo compression? I stupidly compressed (LZW) some tiff files, put weeks of work into them and just realized I don’t want any compression. I’m laying out a book in Photoshop – illustrations and text.
Can anyone help me or at least tell me the harsh reality that i have to redo all the files?Thanks!
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8 Replies
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You can do a Photoshop Save AS save as back to Tiff and remove the LZW , and your image most likley will still print very good. Many RIPS hang if LZW is on the file, so they may fail to print the file. LZW is a lossy compression though, so you cannot get the quality back you lost.
There is a filter reduce noise in phothsop which is uspposed to get rif of jpeg artifact, though I have nto had good results with it, you may want to try it on you un LZWed file. Median may also help.
PSD is a format that has compresison, but is not lossy, I use it all the time as many Adobe apps InDesign/After Effects/Illustrator let you place PSD.
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Hey Mike-
I’ve read the specifications of the LZW algorithm and it states that LZW compression is lossless. I save much of my work in TIFF LZW format, and am concerned by you post.
Could you elaborate on the lossy attributes of LZW or direct me to some documentation?Thanks
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Vince is right, my memory slippd on that one. LZW is a 100% a non-lossless compression. You should only have to do a save as and uncheck LZW, and your file will be back to original quality.
Sorry for the scare, but alteast a happy ending.
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Yeah, LZW goes back to the days where computers were struggling with a “50 MB” file. Now computers are so much more powerfull that there’s no reason to use lzw compression any It causes more trouble on some RIPs than there is benefit . I think designers just check that LZW button, because they’ve done it for years this way…just a bad habit 😉
Adi -
I use LZW compression to save disc space. It is not a bad habit, when you can save up to 90% of your disc space by using LZW.
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Have you tried printing your image as an RGB file. Wanting to make sure you had received my post as it will make a world of difference.
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my last post wound up under the wrong topic somehow. This was supposed to be a reply to rgb -vs- cmyk. Sorry again.
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Thanks a bunch!
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