Originally Posted by
teckat
Depending on how you are creating the PDF you can change the PDF settings, the Standard (default) settings might be applying too much compression. Try changing your PDF Settings (joboptions) to High Quality Print:
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In principle, it is possible to print a PDF through some chain of programs that ends in a PDF generation with no quality loss.
Two major things have to happen to guarantee a perceptually lossless conversion:
Every link in the chain has to understand all of the document elements, and be able to pass them along to the next piece in the chain losslessly:
If the document contains embedded fonts, the font must also be installed somewhere the PDF writer can find it so it can re-embed it, or the embedded font has to somehow be passed through the chain.
If the document contains embedded applets — JavaScript, Flash, Postscript... — they have to be passed along untouched.
If the document contains hyperlinks, active forms, OCR text layers, custom page numbering, non-printing markup, comments, metadata, etc., all the pieces along the chain have to know how to pass this data through to the writer.
If the document contains mixed page sizes, the programs in the chain have to be capable of that trick, too.
No link in the chain may reinterpret any data passing through it. It is common in PDF chains for images to be resampled and converted to more efficient lossy formats, for example.
Even if the images in your original PDF are already low-DPI JPEGs, the pieces in the chain might choose a different DPI or have a different compression level setting.
(By the way, the mere fact that there is a JPEG on either or both ends of the PDF-to-PDF chain technically means the chain is not lossless, unless the raw JPEG data is being passed through as-is somehow. However, it is possible for a recompression step to be perceptually lossless. This does not always happen, however, sometimes on purpose.)
It is possible to achieve a perceptually lossless conversion but lose editability or end up with a substantially larger file:
A PDF document containing text which was created from a primary source (that is to say, not a scan or conversion from some other document presentation format) usually contains the actual text and font data that lets the PDF reader draw the text on the screen in the same way a word processor does.
It is possible to turn such text into 2D raster or vector art in a perceptually lossless fashion. PDF even allows you to preserve searchability and screen reader accessibility by use of non-printing OCR text layers. However, such a conversion would balloon the file size and make editing much more difficult.
Vector art may be rasterized, using DPI equal to or an even multiple of the print/viewing DPI.
The chain could convert all JPEGs to TIFFs, so as to lose absolutely no image quality.
The chain could involve JPEG to JPEG, with no DPI change, but use a high fixed quality setting so as to avoid creating perceptible artifacts.
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