Ignore Drop shadow resolutions

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nikj
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Ignore Drop shadow resolutions

Post by nikj » Tue Sep 14, 2021 7:57 am

Hi,

I have a preflight profile that's set to fail images that are under a specific ppi, unfortunately when a pdf contains a drop shadow that's been created in InDesign the PDFs fail due to lowres images. Even when the Transparency flattener settings are set to the highest in the document the drop shadows are still created with a ppi that's under my profiles minimum limit. Is there anyway to detect/exclude drop shadows when checking image resolutions in PDF?

Thanks,
Nik

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magnussandstrom
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Re: Ignore Drop shadow resolutions

Post by magnussandstrom » Tue Sep 14, 2021 10:23 am

Hi Nik, because of this same issue we have actually set our standard resolution check to 149 ppi. If the job is very high end we add another preflight that will warn if images is below 250 ppi. We have been working like this for years and had no complains from customers regarding image resolution so far.
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magnussandstrom
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Re: Ignore Drop shadow resolutions

Post by magnussandstrom » Tue Sep 14, 2021 10:26 am

One more comment - The reason that drop shadows and similar objects get 'rasterize' is because of the use of an older PDF version in the Export settings. I would recommend you start using PDF/X-4 which doesn't rasterize these objects.
Last edited by magnussandstrom on Tue Sep 14, 2021 11:11 am, edited 1 time in total.
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nikj
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Re: Ignore Drop shadow resolutions

Post by nikj » Tue Sep 14, 2021 11:00 am

Hi,

many thanks for your reply.

I think your approach is probably the way I need to go. We preflight files that can be as small as a business card or over 6 metres wide and although I dynamically set the preflight resolution based on the size, the ratio isn't perfect, this is only complicated further by drop shadows being a low resolution than any images that may have been included.

I'll take a look at the PDF/X-4 export preset and see if I can accommodate some of the settings in our preset.

Thanks,
Nik

freddyp
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Re: Ignore Drop shadow resolutions

Post by freddyp » Tue Sep 14, 2021 3:40 pm

If the drop shadows have a property that distinguishes them from the other images, e.g. because they are in a different color space like DeviceGray, you can also check the image resolution in an Action List because there you can use selections.

A lesser known Action, but a potentially interesting one in this context is "Select black and white objects". If you AND it with "Select images" it will also select CMYK images that are black and white only which could be a way of qualifying them as drop shadows.

I try to be careful in the way I word this, because when you have red drop shadows, this will not work of course.

nikj
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Re: Ignore Drop shadow resolutions

Post by nikj » Tue Sep 14, 2021 3:53 pm

Hi Freddy,

thanks for your reply.

Are you saying that I could select the black and white images in an action then force them to upsample to a minimum res and then preflight it using my existing profile?

I get what you're saying about different colour shadows.

Thanks,
Nik

freddyp
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Re: Ignore Drop shadow resolutions

Post by freddyp » Tue Sep 14, 2021 4:22 pm

I am saying that you can select black and white images. What you do with what you selected is up to you. Upsampling them is one possibility, but you could also turn around the selection with NOT and then check the resolution so these images do not get included in the check.

nikj
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Re: Ignore Drop shadow resolutions

Post by nikj » Tue Sep 14, 2021 8:10 pm

I've created the following action and I intend to run this before my PitStop Preflight Profile is run:

• Select all
• Select grayscale images
• Select if image resolution less than 201dpi
• AND
• Resample image

So far this is upsampling only grayscale images that have a resolution lower than 201dpi, any CMYK images with a higher or lower res are left untouched.

Thanks for all the input,
Nik

freddyp
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Re: Ignore Drop shadow resolutions

Post by freddyp » Wed Sep 15, 2021 8:37 am

You are possibly already doing this, but you wrote "to run this before" and from experience I know that people sometimes do this in two steps by chaining 2 instances of the PitStop Server configurator, so just to be on the safe side: there is really no need for that. When you use Action Lists and a Preflight Profile in the PitStop Server configurator the Action Lists are always executed first.

An alternative is to add the Action List in the eponymous section of the Preflight Profile. In that case the Action List is baked into the Preflight Profile so to say.

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