[Coco] Re: [Color Computer] Requesting .pdf help...

James Diffendaffer jdiffendaffer at yahoo.com
Mon Jul 18 10:55:33 EDT 2005

--- In ColorComputer at yahoogroups.com, "Michael Wayne Harwood"
<michael at m...> wrote:
> test2.pdf is a multipage .pdf file with 10 test pages.  To get this
> quality I had to resize the image to 100ppi (782x1082 in this case)
> I published to .pdf.  A source image at 100ppi does not go though
most OCR
> engines very well.
> Let me reiterate that I am NOT trying to re-open the .djvu vs .pdf
> - please focus your replies on advice and practical examples of how to
> accomplish these goals in the .pdf format.
> Regards,
> Michael Harwood

The reason you are having to shrink the image down is because your
scan has large areas of color that, look the same to the human eye, 
but it's composed of thousands of pixels differening in color.

Since djvu approximates the image (lossy) it isn't a problem.  
PDF is trying to create vectors to store all of them (non-lossy).
If Acrobat has some sort of option that eliminates this you'll have
better luck. 

If you want to stick with the large file but get better compression
you could pass the images through some sort of image processing that
eliminates the isolated pixels.  It would probably make both programs
compress better.  Smoothing filters do that.  It's how they remove
moles and freckles from cover models so they appear to have perfect
skin.  But it causes indiscriminant fuzzing of the image and those
photos are edited by hand... not automated.  I'm not sure what would
be a good alternative.

The large scale document archival systems I've worked with all expect
B&W source images (order forms, membership applications, etc...) so
I'm not sure what would work well for color.

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