Smudging of pages containing grayscale images

[Lord_Snooks@adobeforums.com]

I've been working on two big historic documents, scanning, cleaning, combining into an Acrobat file. One has started producing a sort of 'smudging' around the clear black text and line art. The other hasn't. The effect only occurs in pages which contain a combination of grayscale and line art. I've made these pages by cleaning up the text and line art, then separately cleaning the grayscale images and pasting them into the page. Pages which contain only line art are not affected.

I can see no setting difference, but I'm aghast at the sight of months of work being degraded.

I've had the same effect in the past with a drawing made up of colour lines. The saved .pdf file has smudged the lines, so what was a crisp, helpful original illustration, which took a long time to produce, is now very second-rate looking.

I prepare pages in Graphic Converter, save to .png, then use Acrobat to 'Create PDF from file'. I'm using Acrobat 6.0.5 Standard.

[Leonard_Rosenthol@adobeforums.com]

The "smudging" you mention is called "artifacting" and happens when an image containing text and/or line art is saved using JPEG compression. So don't do that!

Leonard

[Lord_Snooks@adobeforums.com]

Thanks Leonard - yes. I had wondered about that, and changed the default compression for grayscale to zip in Distiller. This seems to have had no effect. (I've restarted Acrobat and Distiller meanwhile). I do observe that if I save my Graphic Converter .png as a .pdf in GraphicConverter, then open and save it in Acrobat, that this appears to prevent the production of the smudging. But as I improve pages, then add them to the main document I need to resave the main document, and each time I do so the document is further degraded. So I'd really like to be able to control this in Acrobat.

It also doesn't explain why one document should show this problem and another not.

I can't see anywhere else to apply such a change?

Best, T.

[Leonard_Rosenthol@adobeforums.com]

Check your conversion settings. Preferences->Convert To PDF.

Leonard

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[Lord_Snooks@adobeforums.com]

Thanks for this, Leonard. I hadn't spotted that I could do this, rather than work through Distiller (and my greyscale was set to zip, rather than lossless jpeg).

Looking at this, and at the manual, I guess I should experiment with the various different types to see what file size I get.

Best, T.