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RE: Compression: was: filmscanners: real value?

Title: RE: Compression: was: filmscanners: real value?

One method I use and am comfortable with for archiving images:

* Scan the image as TIFF (48 bit) from a Canoscan FS2710 (30-40mb image)
* Do colour correction in photoshop.
* Convert to 24bit Colour Save back as TIFF
* Use ACDSEE with Luratech Wavelet compression and batch convert all TIFF's to LDF using Quality setting of 88% which yields about a 2mb image (same as JPEG) but on closer inspection doesn't have the artifacting of JPEG. 

* I would save as 48bit in LDF but it doesn't support it.

JPEG is a good "final image" format, to my eye there is no discernable image loss, but should you want to store the images for reworking I find I run into problems with JPEG when using some filters such as sharpening.

Writing/Reading LDF is about 3x slower (best guess) than JPEG.


-----Original Message-----
From: Alan Tyson [mailto:AlanTyson@bknowl.freeserve.co.uk]
Sent: Friday, February 02, 2001 6:37 PM
To: filmscanners@halftone.co.uk
Subject: Re: Compression: was: filmscanners: real value?


For those of us working at 2700dpi....

When you've got a final image with which you're really
happy, I find Ed Hamrick's choice of "90% jpeg quality" or
my own choice of "15% compression" in PaintShopPro to be
barely distinguishable at a pixel level from the original.

This typically saves a 27MB uncompressed 24-bit colour
photographic image as just over 2MB, and means 300-odd
instead of 25-odd images on a CD-R. Also, on my antique
2-year-old machine, reading and decompressing a 2MB jpeg is
enormously quicker than reading a 27MB tiff from disk or CD.


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