White / Blank space area calculation

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Toby
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White / Blank space area calculation

Post by Toby »

Is there a preflight or action that can calculate the square inches of white/blank space (areas with no ink) within a PDF?
or vice versa, the square inches of a PDF covered with ink (not TAC or density, just page coverage).
This is to help estimate the amount of Optimizer Ink needed for print.
Thanks
freddyp
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Re: White / Blank space area calculation

Post by freddyp »

There is an action that calculates the ink coverage for all inks (Gather ink information). So how about the surface of the page minus the ink surface? That will not work.

The first reason is that the ink coverage calculation takes into account the percentage values: when an ink at 50% covers half the page surface that means the ink coverage is 25% for that ink.

The second reason is that the ink coverage calculation gives a result per ink: when ink areas overlap you can quite easily achieve a combined value of more than 100% even when there is still white on the page. Put differently, the page surface minus the sum of the ink coverage surfaces of all inks could be negative.

I can think of a method to calculate the white area. I will have to do a few tests first but before I do that I would like to understand why you want to know the white surface area? I do not understand "this is to help estimate the amount of Optimizer Ink". What is "Optimizer Ink"?
Toby
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Re: White / Blank space area calculation

Post by Toby »

Thanks for the response Freddy.
You listed the problems I ran into.
'Optimizer Ink' is used by HP inkjet presses, a negatively charged 'optimizer' ink layer is printed on the paper prior to positively charged CMYK ink.
It can be thought of as a base coat that will only be printed where CMYK will be printed. This is why I need to know either the page area coverage (percentage or square inches) or total negative/white/blank space by square inches within the PDF.
Toby
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Re: White / Blank space area calculation

Post by Toby »

Does anyone else have any ideas?
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JimmyHartington
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Re: White / Blank space area calculation

Post by JimmyHartington »

I have made an action list which rasterizes the page.
Converts to grey.
Inverts the image.
Crops to trimbox.

This is then integrated into a preflight, which gives me these numbers for ink coverage:
Image

Can that work for you? Since I invert the grey image, then the black values should be the white of the page.

The preflight and sample file can be downloaded here: https://d.pr/f/LNA50A+
Toby
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Re: White / Blank space area calculation

Post by Toby »

Very smart solution!
Thank you Jimmy!
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JimmyHartington
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Re: White / Blank space area calculation

Post by JimmyHartington »

So you can use it?

Glad to help.
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