I am resending this - the firsts attempt with the attachment didn't make 
it apparently . . I can provide it if anyone is interested . .

On 2010-06-24 10:08, Chris Mohler wrote:
> On Wed, Jun 23, 2010 at 5:30 PM, Leon Brooks
> <>  wrote:
>> If the image is text or something else essentially
>> monochrome
> Or image->mode, bitmap, 1-bit palette should drastically reduce the
> file size.  I suspect that the 'line art' setting in xsane is
> producing a grayscale image but with each pixel either solid black or
> solid white, which would make the resulting PNG easy to compress.
> Rotating likely causes many pixels to become shades of gray along the
> edges and increasing the file size.
> My scanner is dead or I'd test this out myself.
> Not sure on the increase when saving the image as-is - are all of the
> 'Save Comment', 'Save Creation', etc. boxes unchecked in the PNG save
> dialog?

I produced a test PNG which resembles my actual pages and confirm my 
previous results - original file attached (it was deliberately scanned 
not square):

    235,913             TestScanningDoc.png
3,184,862               TestScanningDoc_-1.0Rotate.png
    374,903             TestScanningDoc_NoChange.png

I used the Gimp defaults when saving the files - compression was set at 
the max of 9.

Confirmation of what is going on from the gurus would be appreciated!

BTW, I got around the real world problem by rescanning my actual pages 
(which were themselves photocopies and NOT squarely produced) by 
manually rotating the pages on the scanner so the pictures ended up 
being square in my PNG and not needing rotation in Gimp (although other, 
minor editing was still necessary).


Philip Rhoades

GPO Box 3411
Sydney NSW      2001

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