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List:       gimp-print-devel
Subject:    Re: [Gimp-print-devel] unprint generates a bad-looking ppm
From:       Robert Krawitz <rlk () alum ! mit ! edu>
Date:       2017-01-12 3:38:16
Message-ID: 20170112033816.DA0C01438FA () localhost
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On Thu, 12 Jan 2017 11:18:29 +0800, Levin Du wrote:
> --001a113f8bd219b79f0545dd2dfa
> Content-Type: text/plain; charset=UTF-8
>
> 2017-01-12 10:15 GMT+08:00 Robert Krawitz <rlk@alum.mit.edu>:
>
>> > But I find another detail. Please see the two images produced by applying
>> > Guten unprint to the print data.
>> >
>> >  - test-jpg-vendor-unprint.png at https://postimg.org/image/4l49uwtcp/
>> >  - test-jpg-guten-unprint.png at
>> > https://postimg.org/image/ywgw4qesz/aaf4a9c9/
>> >
>> > (test-jpg-guten-unrpint.png is produced by setting escp2_density to 2.4
>> in
>> > model_80.xml)
>> >
>> > Open them with Gimp, zoom in to 16x, compare the solid color of red,
>> black,
>> > etc
>> > of both images. I find that the vendor driver makes good use of white
>> color,
>> > while Gutenprint doesn't.
>>
>> What am I supposed to be looking for?
>>
> For example,
>
> solid black: https://postimg.org/image/7sr115o3z/
> solid red: https://postimg.org/image/7sr115o3z/

You can't use unprint at this level to determine correct density
settings.  It does not model dot gain and other physical effects.
You'll need to actually make prints to see what happens.
-- 
Robert Krawitz                                     <rlk@alum.mit.edu>

***  MIT Engineers   A Proud Tradition   http://mitathletics.com  ***
Member of the League for Programming Freedom  --  http://ProgFree.org
Project lead for Gutenprint   --    http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton

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