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Question

Exported PDF looks a bit jagged pixeles between areas

Forum|Forum|2 years ago
February 12, 2024
6 replies
957 views

I've made a layout in InDesign with a placed high-resolution PDF. 
(The PDF are exported with Acrobat 4 (PDF 1.3) and contain high resolution images.) 
When I export the layout from InDesign with the job options I got from the printer, it looks a bit 
pixelated in one place in the image. 
Is it just the preview, or will it be like that in print? Can I do another export to avoid it?

I've tried to export with compability Acrobat 5 (PDF 1.4) and higher, but got the same result.

This topic has been closed for replies.

Brad @ Roaring Mouse

Community Expert

Exporting any PDF, even from original material, less than PDF 1.4 will cause the resulting file to be flattened. This will cause all the areas affected by any transparency effects, drop shadows, etc, etc, to be rendered as individual tiles of images pixels.

Depending on what compression TYPE and level of quality you use, these tiles may fit together with some anomalies. e.g. Bicubic Downsampling, although very good in many cases, causes doubled up pixels on the right edges of these image tiles due to a ;imitation of the algorithm used.

If you open one of your "bad" PDFs in Illustrator, you can see how these tiles fit together, and also if you zoom in, you can see how the last column of pixels is almost an exact copy of the one to its left... like so:

You can see the area that you've shown us (circled) is at the edge of one of these "tiles".

So, firstly, DO NOT save less than PDF 1.4. For that matter, even 1.4 is very outdated in a modern day production environment.

Secondly, consider changing your PDF export setting to Average Downsampling instead of Bicubic Downsampling... you'll not see any difference in the final result, but because Average works on a completely different algorithm, it doesn't need to create this double-pixeling.

K

kajsaliAuthor

Participating Frequently

Thank you for this brilliant explanation. Wierd thing that I got the joboptions from the printing company...

Kajsa Lindh
Art director / Graphic designer
är part of the big plan

Tel: 0704-82 00 03
thebigplan.se

K

kajsaliAuthor

Participating Frequently

Thank you, I got the original InDesign files and made a PDF from this. No PDFs of PDFs of PDF...

Thank you all for your answers/help.

JR Boulay

Community Expert

High-resolution printing usually starts between 250 and 300 dpi, but this image is at just 230 dpi.

And it looks highly compressed, as you can clearly see banding effects and artifacts when zoomed in at 200%.

Acrobate du PDF, InDesigner et Photoshopographe

Derek Cross

Community Expert

What is the Effective PPI of the placed image in InDesign?

rob day

Community Expert

The PDF output res is 230ppi

There are telltale signs of upsampling and double JPEG compression—a combination of small and large JPEG artifacts, which wouldn’t happen with a placed .PSD that has not been sampled up, exported with the default Compression settings:

rob day

Community Expert

You can also spot upsampling by zooming in on high contrast edges. This image on the right was sampled down to 100ppi then back to 300ppi—the upsample either causes severe blocking, keylining, or both along the edges:

rob day

Community Expert

The 230ppi image looks like it was sampled up in Photoshop(?) and compressed (saved as a JPEG), before you placed it in InDesign. Can you share the placed image?

K

kajsaliAuthor

Participating Frequently

Here´s the PDF

2_XL_Bygg_Götene.pdf

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