Re: dpi and line screen -- Conventional Wisdom vs Reality
Re: dpi and line screen -- Conventional Wisdom vs Reality
- Subject: Re: dpi and line screen -- Conventional Wisdom vs Reality
- From: Jim Rich <email@hidden>
- Date: Thu, 29 Dec 2005 16:12:39 -0500
- Thread-topic: dpi and line screen -- Conventional Wisdom vs Reality
Title: Re: dpi and line screen -- Conventional Wisdom vs Reality
There have been a few articles on this and all done agree.
Here is an almost exact quote that is taken from the original Photoshop in Black and White Book that was published in 1992.
“The rule of thumb for input resolution is based on the NyQuis Therom. That is, when you are going to print, use twice as many input pixels (2:1) as the halftone screen ruling. While this 2:1 rule of thumb is a good starting point to determine image resolution, some imaging professionals have experimented with reducing input resolution and have found that it is possible to achieve good results with as low as 1.5:1 input image resolution for halftone printing. To determine input resolution, the best method is to run several tests at different resolutions and choose the best results. “
Also in 1992 we ran some tests for halftone printing using ratios from 1:1 to 2:1. We found that in some cases when using less than 1.5 :1 that the images were pretty safe. However, we also determined that if you use a lower resolution image (sch as with the 1.5;1 ratio) you can compromise the image quality if any of those lower resolution images are scaled up say in Quark. And if that happen you then might have to rescan the original at a higher resolution. If that happens every now an then its not a problem, but if it happens say to hundreds of images your hosed.
As for images below the ratio of 1.4:1, we found that you can get away with the lower resolutions but it became image dependent.
That was then.
Today, for offset printing my sense is that those guidelines still apply. But for other processes like inkjet printing you can get away with less image resolution. You just have to run a few tests to determine the optimum input resolution.
When it comes to resolution, mileage will vary.
Jim Rich
On 12/29/05 3:21 PM, "Richard Frederickson [Contr]" <email@hidden> wrote:
Please pardon my being a bit off topic with this post, but I thought with all the experts out there who monitor this forum, I'd get the most reliable response to the following:
Conventional wisdom says to provide twice the resolution of your line screen for offset printing. I seem to remember reading an article debunking that myth and promoting a resolution equal to line screen scenario--but I can't put my hands on it.
Can anyone point me to an authoritative source I can quote?
Many thanks!
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