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JGP compression for WEB posts

  • From: P3D Ralph Johnston <copley@xxxxxxxxxxxx>
  • Subject: JGP compression for WEB posts
  • Date: Sat, 20 Sep 1997 09:03:53 -0400
I recently scanned realist print pairs done by Grand Photo, Minneapolis,
and posted them in my cat web page.  The size was reduced from the original
TIF file by using Corel Photopaint 7, save-as, JPG, compression=20.  The
program lets you select compressions from 2 (good) to 256 (poor).

	See http://www.ultranet.com/~copley/catsin3d.htm

Last night I saved another image with compressions ranging from 2 to 256
and examined them.  It turned out that only above 180 could I tell any
difference.  I settled on 128.  Below are the sizes vs compression number:

Original TIF scan		9Meg		1500 x 2100 pixels
JPG Comp=2		267K		436 x 600 pixels
	20			123K
	40			80K
	80			54K
	120			42K
	128			41K
	160			36K
	200			26K
	225			19K
	256			8K

Based on the above I am going to resample it at 800 pixels wide and use 128
compression.
*****************************************************************
*   Linda Sherman/Ralph Johnston
*   LINMAR PERSIANS
*   Solids, Bicolors, & Tabbys
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