TAKO. INTERNET SEIT 1996.
Olympus-OM

Re: [OM] Olympus Calendar in Electronic Format? Think Again!

Subject: Re: [OM] Olympus Calendar in Electronic Format? Think Again!
From: Garth Wood <garth@xxxxxxxxxxxxxxx>
Date: Tue, 20 Jan 1998 23:21:24 -0700
At 11:35 PM 1/20/98 +0100, Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx wrote:

>What you have done, is to confuse the resolution in dpi of the printer
>with the halftone resolution of the image. 
>The printer needs for his press a higher printing resolution to simulate
>halftones.
>If you want a 300 dpi or 150 lpi resolution for your image 8 x 10 you
>have to calculate:
>
>8X10=80 square inch
>
>300x300=90,000 pixel 
>
>90000x800=7,200,000 image pixel
>
>each pixel has 3 byts 24 bit, because you should not separate in CMYK
>before you know your printing device to match. Without Postscript and
>just Mac or Windows OS it´s futile to separate images because this OS
>only know RGB colors.
>
>7,200,000pixel x 3 byte = 21,600,000 byte or roughly 20 MB
>
>20 MB is still a impressive size for one image. The grid is a PS vector
>file which counts not much.

Richard:

Please go back and read my original post -- you'll see I'm not wrong (in
fact, your final set of calculations essentially agrees with mine for the
300 dpi scenario, adjusting for the fact you're talking about an output
device which can produce 256 levels of luminance for each pixel, while I
wasn't).

My point is simple: depending on target resolution and output device
(remember, the original poster suggested that we distribute this as a .PDF
file, which is device-independent but, FOR RASTER IMAGES, *not*
resolution-independent), the files could be unacceptably huge.  I've
produced single-page monochrome files as .PDFs with a target resolution of
2450 dpi that have been in the 50+ Mbyte range when a raster image was
included.  Thus my subsidiary point about particular target devices
(dye-sub printers) producing good results even with modest resolutions (300
dpi) and large printouts (8"x10" or better) -- the printing algorithms in
such devices, combined with chemo-mechanical processes involved, can
"interpolate" huge amounts of otherwise-missing "point" data.  I've seen
dye-subs produce output that tricked me into believing I was looking at a
photo until I got the loupe out.

Tomoko's post about the output from her inkjet printer (I'm assuming it's a
360-dpi device, Tomoko?) gives a much better indication of the kind of file
size for even relatively modest resolutions, and while inkjet may be
acceptable for some people, I'm sure others would be disappointed in an
effort that produced results they considered "inferior."

By the way, Tomoko, I like your suggestions.

Peace, everyone.  It's late, and I need my sleep.

Garth

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