DEC scanned documents for Bitsavers (message for Al Kossow)

Paul Koning paulkoning at
Fri Apr 24 10:03:56 CDT 2015

> On Apr 24, 2015, at 11:00 AM, js at wrote:
> On 4/24/2015 9:46 AM, Paul Koning wrote:
>>> ...
>> I would not call 90 dpi “good enough”.  The professional printing rule of thumb is that for an n grayscale dots per inch halftone image you need 2n DPI resolution.  So 90 dpi is, at best, low grade newspaper resolution.  A standard commercial grade scan for good quality printing is 260 dpi or so — which means 300 is certainly a fine choice.  150 or below may well be acceptable if that’s the best you can get, but you’re definitely compromising image quality if you do that.
> Why don't you actually try it.   Also, I'm assuming reading on a screen (where I read most of my vintage manuals) vs. re-printing.  My screen resolution is 90dpi.  Anything over that is pure waste.   Maybe you have better eyes than I do, but I can't discern image quality over 100-200dpi for printing.

You’re assuming I haven’t.  In fact I have done scans for a long time, with different resolutions; my comment was not based on ignorance.  Ditto my statement about professional printing practice.   And while a lot of computers have 90 dpi screens, some (like mine) are substantially better.  Finally, depending on your eyes you might well be reading at greater than 1:1 scale.


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