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[Bug-ocrad] reading color images
From: |
Erik Auerswald |
Subject: |
[Bug-ocrad] reading color images |
Date: |
Thu, 16 Feb 2006 20:26:35 +0100 |
User-agent: |
Mutt/1.5.11 |
Hi,
I've noticed that GNU Ocrad 0.14 implements reading of color images and
looked at the code (without testing it). You seem to use the formula
greyvalue = min(red, green, blue)
which does not at all work like the human eye. I would recommend using
one of the following two formulas:
greyvalue = 0.2125*red + 0.7154*green + 0.0721*blue
greyvalue = 0.299*red + 0.587*green + 0.114*blue
To see the results of these formulas take a look at
http://www.unix-ag.uni-kl.de/~auerswal/ssocr/greyscale.html
(contains about 1.4 MB of image data).
For information about color specification in images see the color FAQ at
http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html
Regards,
Erik
P.S. I'm not subscribed to this list, so please cc: me if you want to
answer me.
- [Bug-ocrad] reading color images,
Erik Auerswald <=