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Convert PDF with color image to Monochrome image

Printed From: Debenu Quick PDF Library - PDF SDK Community Forum
Category: For Users of the Library
Forum Name: I need help - I can help
Forum Description: Problems and solutions while programming with the Debenu Quick PDF Library and Debenu PDF Viewer SDK
URL: http://www.quickpdf.org/forum/forum_posts.asp?TID=2992
Printed Date: 12 Aug 20 at 3:56AM
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Topic: Convert PDF with color image to Monochrome image
Posted By: John_Hagglof
Subject: Convert PDF with color image to Monochrome image
Date Posted: 16 Oct 14 at 8:38AM
Hello,

I need to:
Convert PDF with color image or greyscale to Monochrome image.
Resample down to 300/200 dpi.

I have Debenu Quick PDF Library 11

Best regards
John



Replies:
Posted By: tfrost
Date Posted: 16 Oct 14 at 11:20AM
In my experience, dithering color to monochrome is best done with a specialist graphics library.  You may have to choose the dithering algorithm to suit the type of image you start with.  Obviously, the availability of good graphics libraries depends on what programming language you are using.

If you start with DARenderPageToStream you can create a color bitmap with the correct resolution and scaling.  Then use your graphics library to convert this to monochrome.  Finally, if your destination happens to be 200dpi fax, convert your monochrome bitmap to a TIF with the appropriate fax encoding.


Posted By: Ingo
Date Posted: 15 Nov 19 at 8:10PM
Hi John,

few years toolate but... ;-)
Here's an older thread dealing with a similar issue.
QuickPDF can do at least a little bit:
http://www.quickpdf.org/forum/forum_posts.asp?TID=2088&KW=monochrome&title=convert-pdf-to-bmb-with-monochrome-color



-------------
Cheers,
Ingo




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