DEC scanned documents for Bitsavers (message for Al Kossow)
paulkoning at comcast.net
Fri Apr 24 10:03:56 CDT 2015
> On Apr 24, 2015, at 11:00 AM, js at cimmeri.com 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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