[pure-silver] Re: Oriental Seagull Papers
- From: "Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 20 Sep 2007 11:07:34 -0500
"Lloyd Erlick" <lloyd@xxxxxxxxxxxx>
"Nicholas Lindan"
> Ink jet can't do _real_ shadows and possibly never will.
... could you elaborate a bit?
It's in the math, simplified it goes like:
Postulate a 300 pixel/inch printer laying down
black ink at 3000 dots/inch.
Each pixel is 10 x 10 dots, or 100 dots/pixel.
If, for an otherwise all black pixel, we calculate:
White Black Reflects OD
Pixels Pixels
0 100 0.01 2.00
1 99 0.02 1.70
2 98 0.03 1.53
3 97 0.04 1.40
4 96 0.05 1.30
5 95 0.06 1.23
10 90 0.11 0.96
100 0 1.00 0.00
There are only 3 tones between shadows at 1.3 OD and black.
And these 3 tones only exist in theory: All the printers I
have tried can't leave one dot white in a sea of black.
The software that drives IJ printers gets around this by
increasing the size of the dark pixels - lowering resolution,
by using colored ink to make a grey so the print changes
tones and/or color in different light, and dithering the dots
so a uniform sea of grey pixels is a random sea of dots
rather than an array of pixels with x dots in them.
Printers advertised for black and white have several shades
of grey ink and ink companies sell special black & white ink
sets. 'Photo Black' is becoming more common in printers.
--
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121
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