Sorry for external reference links!!!!!
As mentioned in the below Adobe help page, When we choose the Adobe PDF 1.4 (Acrobat 5.0) or later version transparency will be retained in the PDF.
Flatten transparent artwork in Adobe InDesign
But now with I am in same situation as in below thread,
High resolution PDF still generates low resolution drop shadows?
My original question is,
My export preset looks like below, and the transparency flattener is disabled. But indesign produced the flattened transparency output with PDF version 1.7.
Can some one help me to understand whether it is a bug in Indesign cc 2017 or do I need to enable/disable anything else in preset/preferences to get the PDF without flattened transparency ?
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Replies
Hi Rob,
just tested a bit on this issue today.
As my experiments are showing:
Up to a size of about 17 mm for a drop shadow resolution for the transparent object is following the flattener's resolution.
From then on resolution will decrease for every mm you enlarge the size of the drop shadow.
The exported PDF begins with a increase of 1 mm for the size of the drop shadow with every page on the same object, a simple square of 10 x 10mm size.
Here I used a custom transparency flattener preset and exported to PDF/X-4.
Before switching back to PDF/X-1 to set the flattener instead the standard one "[High Quality]".
( Note: The name of the flattener preset on the page does not match the one used for PDF export. )
Flattener settings: 100% for Pixel/Vector Balance, 1200ppi for all other elements.
As you can see from the results in this screenshot, this time drop shadows from 1 to 4 mm follow the flattener.
Drop shadows bigger than 4 mm will enforce resolution to go down dramatically.
If we compare screenshots 1 (flattener with 300ppi) and 3 (flattener with 1200ppi) one can see, that it might help to choose a higher flattener resolution in some situations, e.g. if you want 450 ppi effective for 175 lpi screening. But I think, that with drop shadow sizes beyond 17 mm or 20 mm every automatic preflight will act up if screens for 150 lpi or higher will be used for printing and the images are tested for 400 or 450 ppi effective resolution or less.
Regards,
Uwe
But I think, that with drop shadow sizes beyond 17 mm or 20 mm every automatic preflight will act up if screens for 150 lpi or higher will be used for printing and the images are tested for 400 or 450 ppi effective resolution or less.
I'm thinking this is more of a feature than a bug. The export from ID is always 8-bit so the shadow can never have more than 256 levels of gray, so the larger the shadow spread the less there is to resolve—the 2:1 ppi to lpi rule of thumb really doesn't apply with a uniform gradient.
So this PDF/X-4 example exports the shadow as 105ppi
At 105ppi the distance from the shadow's darkest value (17%K or roughly 215 8-bit) to white is 250 pixels. There are only approximately 40 gray levels available to define this gradient so adding more resolution wouldn't change the gradient's appearance
Edit>Transparency Flattener Preset to open the transparency Flattener Panel.
Click New
Specify the Options as the photo and Name it.
When exporting to Adobe PDF (Print)
transparency flattener preset is disabled in the Advanced section, to enable it choose from compatibility: Acrobat 4 (PDF 1.3)
Now the preset is enabled, choose the preset you defined and then you can change the compatibility again to Acrobat 8/9 (PDF 1.7) .
Make sure that you use Adobe PDF Preset PDF/X1a (2001 and 2003) that flattens transparency using the High Resolution setting.
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