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I am having problems with printing some PDF documents on a 2014 MacBook Pro running macOS 10.14.3.

Most PDF documents print fine (from Preview), and I'm happy with the quality.

Examples are these two: Good quality. Also good quality.

However, I'm having issues with a specific paper.

In Adobe Reader and Preview, the quality looks good, and the letters are very sharp.

But something different happens when I print:

Firstly, from Preview: Poor quality print Now from Adobe Reader: enter image description here

This is annoying.

Why is it doing this? Presumably there's a problem with the pdf. But what could it be, and how can I fix it? The pdf looks fine in Preview and Adobe!

For reference, this is the paper I am trying to print.

  • Welcome to Ask Different. Each printer company has guidelines to follow when printing on specialized paper. This doesn't appear to be an Apple issue. You need to contact your printer manufacturer for the correct settings to use with this paper. – fsb Feb 19 at 21:45
  • Hi, thanks for your response. The paper is standard A4 paper. All the prints (good and bad) are on this paper. Furthermore, the test pages I have printed on this paper are all good quality. – J. Jaksche Feb 19 at 21:46
  • Can you try printing from a different device? The goal is to isolate the problem and determine if it's the printer or the Mac with the issue. Also, please edit your question to include the type of Mac and macOS you're using. – fsb Feb 19 at 22:42
  • And, just to clarify, you're saying this issue is with the single linked PDF, and not PDFs in general? – Alex Feb 19 at 23:22
  • There is something wonky with the file — I get the same effect when I render it onto PNG bitmaps with Ghostscript. – Ture Pålsson Feb 20 at 9:35
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I have observed this problem before: seemingly solid-tone 100%K text or other vector image in a PDF gets printed out with a 'dotted' pattern.

The problem is caused by color definitions in the PDF file, which get rasterised into 'half-tone'. So you end up with an object that is 100% Black, but comprised of dots, rather than solid tone.

The solution is to make sure that Color Matching is switch to "In Printer" and NOT to "ColorSync". This for Preview and other Apple apps. In Acrobat, use "No Color Management".

I printed sample pages from your exemplar PDF, and they were fine. The PDF is non-optimal, admittedly, as there is Transparency and mixed CMYK and RGB objects.

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If you’re having issues with a single PDF and not others, the issue is with that file and not with your viewing application (Preview, Acrobat, etc.)

The problem comes from how the PDF was rendered. The lower the DPI, the less data there is to render graphics. What’s rendered for the screen doesn’t necessarily translate to a good rendering on printed output. For example, 50 DPI (for text) might look just fine on your screen, but to get clear text in print, you likely need about 200 DPI.

Additionally, the paper may have been rendered as an image when the PDF was created rather than a native PDF text document.

Unfortunately, there’s no way to fix this other than re-rendering the document. If you don’t have access to the original, you may be able to OCR it, use your favorite editing tool (Word, Pages, etc.) to “remaster” it, and then render that document with a higher DPI.

  • I imagined this would be the case. That's a good idea to use OCR - thanks! – J. Jaksche Feb 20 at 15:58
  • I don't think it's a simple resolution problem. The file renders perfectly on screen, even at high magnifications. When rendered to a high-resolution bitmap with ghostscript, you get a regular pattern of dots that do not look like sampling artifacts. I thought passing -dPrinted=false to ghostscript might change this, but that had no effect. I suspect this is some sort of copy-protection measure put in place to discourage from printing the file, but I do not know how it works. – Ture Pålsson Feb 20 at 17:00
  • When rendering with Ghostscript, the problem only seems to happen with "pure" black-and-white output formats such as pngmono or pbm, not with png16m or ppm. Curiouser and curiouser... – Ture Pålsson Feb 20 at 17:12

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