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Topic: Anti-aliasing problem with images (Via Email), 2 Attachments
Conf: (P-PDF) Acrobat 6.0, Msg: 140841
From: shoobi
Date: 10/7/2005 03:59 PM

Hello,

I have problems with image anit-aliasing when images get resampled. I am trying to create a PDF from a Visio drawing that contains a rotated image. The image probably gets resampled due to the rotation. The result is an image with an wrong anti-aliasing. That is, there is a smooth color change at the border where there should not be one. The smooth color change would only make sense if the image would not have been rotated. This is particular visible at the border. The border looks inclined, but this is just an optical illusion coming from the wrong anti-aliasing.

This strange effect only happens with Acrobat 6; it worked fine with Acrobat 4. I used exactly the same settings. I used a very high image quality in the settings (downsampling to 600dpi); these settings do not have any effect on my problem, however. I even turned anti-aliasing on directly in the .options file.

Attached you find two screenshots to show the effect. Any Idea?

Thanks,
Shoobi

straight border, Acrobat 4.png
Acrobat 4 (25,690 bytes)

unsteady border, Acrobat 6.png
Acrobat 6 (19,006 bytes)