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apprenticeharper / DeDRM_tools

DeDRM tools for ebooks
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Image distortion in PDF #1056

Open stefan-plate opened 4 years ago

stefan-plate commented 4 years ago

I've had this problem for a while, now checked again using the latest Calibre Plugin (6.7) on macOS 10.15: Some images in the decrypted PDF are distorted like this:

Screen Shot 2020-04-11 at 17 09 23

While the original looks like this:

Screen Shot 2020-04-11 at 17 13 52

I did not find a similar issue here. This happens infrequently and I don't see a pattern.

ElleKayEm commented 4 years ago

Is this in the calibre viewer? Or the same program that you're using to view the original pdf?

stefan-plate commented 4 years ago

It looks excactly the same in macOS Preview and Adobe Acrobat. The original document only opens in Adobe Digital Editions due to DRM.

ElleKayEm commented 4 years ago

No conversion? Just DRM removal?

stefan-plate commented 4 years ago

Absolutely. Downloaded with Adobe Digital Editions (current version), pulled the PDF into calibre (with current DeDRM Plugin) and opened the resulting file. Just DRM removal, no conversion. BTW the result is the same if I use the standalone DeDRM app (which I understand is not updated anymore).

ElleKayEm commented 4 years ago

Seems like something @apprenticeharper will need to look at. It may be a while before he gets a chance to see this here. You could try contacting him at apprenticeharper@gmail.com.

rosshjb commented 3 years ago

From https://www.adobe.com/kr/solutions/ebook/digital-editions/faq.html :

Why do some PDF documents look different in Digital Editions than they do in Acrobat and Reader?

Digital Editions utilizes Adobe PDF technology that has been optimized for small code size and lower system requirements. It is optimized for performance and onscreen readability, rather than graphic arts or prepress-level fidelity. As a result, some minor differences in graphics and font rendering are to be expected. In addition, the Digital Editions PDF implementation does not support several enterprise-oriented PDF features. These features are not typically used in PDF-based eBooks, and if present, they are ignored but may cause certain documents to render incorrectly.

I think that your problem is caused by Adobe Digital Editions. I am experienced same problem too.