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Re: filmscanners: File format

Just a note on LZW compressed image portability - I have run into one
instance where an LZW compressed image was not portable - when exporting a
48-bit compressed TIFF from Vuescan to Corel PhotoPaint 9 it opens but the
image is unrecognizable.  If exported uncompressed there is no problem, and
once in PhotoPaint it can be compressed using LZW.  This appears to be one


----- Original Message -----
From: "Rob Geraghty" <harper@wordweb.com>
To: <filmscanners@halftone.co.uk>
Sent: Thursday, March 29, 2001 10:15 PM
Subject: Re: filmscanners: File format

| larry wrote:
| > What would be the point of storing and reopening and saving
| > the same image in a compressed format repeatedly. Each time
| > there would be some generational loss.
| This is only true of lossy compressed formats like jpeg and PCD.
| > Store in an uncompressed native format to your graphics
| > program.
| This is slightly faster, but not actually necessary.
| You can use a lossless compression.
| > If you open a jpeg in Photoshop it automatically takes on
| > the characteristics of a PSD. That's why you should save
| > it as a PSD prior to working on it. Then use Photoshop's
| > "Save for the Web" to create your compressed jpeg.
| Just to paraphrase slightly, the best option is to keep
| a master copy of the image in a lossless format, and
| only convert a copy of the image to jpeg at the point
| when it has been edited to the final requirements.
| I use LZW compressed TIFF because it is transportable
| between different editing programs.
| Rob
| Rob Geraghty harper@wordweb.com
| http://wordweb.com


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