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Old 11-07-2005, 10:58 AM   #1
Molly/CA
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Default Count DPI in printed pic?

We'd like to, or need to, know exactly the dpi a certain press's illustrations in a certain series are being printed at. Is there any easy way to figure this out? We do have a dissecting microscope. Uh, (blush) dumb question, dpi is a linear measurement, isn't it? Dumb question II, are the dots' allotted spaces square?

Thanks again, all you experts and professionals.

Molly
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Old 11-07-2005, 01:27 PM   #2
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Quote:
Originally Posted by Molly/CA
We'd like to, or need to, know exactly the dpi a certain press's illustrations in a certain series are being printed at. Is there any easy way to figure this out? We do have a dissecting microscope. Uh, (blush) dumb question, dpi is a linear measurement, isn't it? Dumb question II, are the dots' allotted spaces square?

Thanks again, all you experts and professionals.
Printers use something called a screen finder (very inexpensive, in the $10 range). It is transparent plastic with an etched grid; you move it around over a printed image until you find a match and read out the linescreen (LPI) used to print the halftone.

LPI is usually 1.4 to 2 times the dot resolution, so if you see an LPI of 133, the scan could have been about 200 dpi — assuming it was scanned at the final size (which is pretty unusual). Because of the size issue it could be tricky to infer accurately what resolution was used to scan. Photos are often scanned at 300 dpi, however.

Ordinary printing on non-coated paper is usually done with an LPI of 133; printing at newsprint can be as low as 65 but is commonly 85 or 90 LPI. Beautiful art books on coated paper could have an LPI of 175 (or even more).

   
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Old 11-07-2005, 01:32 PM   #3
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Expect Peter Arnel to chip in real soon boasting that he does 200 lines as standard!
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Old 11-07-2005, 02:14 PM   #4
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Expect Peter Arnel to chip in real soon boasting that he does 200 lines as standard!
Oh, well — we should expect no less!

But Molly does not seem to be dealing with a Peter class of printer. I am sure she would prefer to!

   
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Old 11-08-2005, 02:02 PM   #5
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hahahaha - of coarse and we are soon going "dotless" great name for Stochastic - printing with 20 micron dots.
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Old 11-08-2005, 02:12 PM   #6
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I think printers who print sheet fed these days are normally 175 - 200# Its only old webs that go down to those low screens.
Peter
The fine art printers are running sometimes up to 300#
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Old 11-09-2005, 12:41 PM   #7
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Kathleen I read this last night - I can never remember seeing one - I have seen one for screen angles . Does it work in a similar way
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Old 11-09-2005, 01:46 PM   #8
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Kathleen I read this last night - I can never remember seeing one - I have seen one for screen angles . Does it work in a similar way
Yes — really low-tech. Lay it on the picture, move it around, line things up, note the reading.

I imagine there must be super-duper high-tech devices for this by now, but these antedeluvian plastic things were very common in my youth.

   
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Old 11-09-2005, 04:00 PM   #9
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Because we dont plan film any more - its all gone
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Old 11-09-2005, 05:48 PM   #10
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Because we dont plan film any more - its all gone
Ah, gee. I am so sorry!

Let’s all move to a desert island somewhere!

   
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