From: Peter Rolf <indiego@gmx.net>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: compresslevel and png graphics (mkiv)
Date: Thu, 26 May 2011 18:17:19 +0200 [thread overview]
Message-ID: <4DDE7D0F.3030002@gmx.net> (raw)
In-Reply-To: <4DDE30D0.9040204@gmx.net>
Am 26.05.2011 12:52, schrieb Peter Rolf:
> Am 25.05.2011 21:54, schrieb Hartmut Henkel:
[..]
>>
>> no. There is a "PNG Copy" function for literal embedding of the PNG
>> file, but that triggers only, if the file simultaneously satisfies quite
>> a few conditions, which are about: non-interlaced, no palette, no
>> transparency, no gamma coming with it, no gamma modification requested,
>> no white adjustment in the PNG, and a few more rare others. Else it's
>> de-compressed and then re-compressed to the \pdfcompresslevel, and
>> additional streams and dicts are added. You see in the log if it finally
>> was "PNG Copy" or not.
>>
[..]
>>
>> These are about the factors affecting the PNG to PDF size. For your big
>> PNG graphic you may find a preprocessing (e. g., pngtopnm | pnmtopng
>> will definitely remove all fat) that makes it compliant with the "PNG
>> copy".
>>
> I will give that a try. But I doubt that there is much 'fat' on that
> graphic. Anyhow, you never know before you have tried it. :-)
>
No luck. I used imagemagick to convert to pnm and back.
Transparency was removed before by adding a white background, also all
not critical chunks (ICC profile, backgroundcolor, resolution, creation
and modify date, comment) were removed. The graphic is a valid PNG
(TweakPNG) and aside from the size, there is nothing special with this
graphic. Still no '(PNG copy)'.
@luigi: an ICC profile definitely breaks the <png copy> rules
The only chunks left are
IHDR PNG image header: 5900x4094, 8bits/sample, truecolor, noninterlaced
IDAT PNG image data
..
IDAT PNG image data
IEND end-of-image marker
Mh, where is the show stopper? The compression method?
Regards, Peter
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next prev parent reply other threads:[~2011-05-26 16:17 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-25 12:43 Peter Rolf
2011-05-25 14:39 ` Hans Hagen
2011-05-25 14:48 ` Taco Hoekwater
2011-05-25 16:05 ` Peter Rolf
2011-05-25 19:54 ` Hartmut Henkel
2011-05-26 10:52 ` Peter Rolf
2011-05-26 11:22 ` luigi scarso
2011-05-26 16:17 ` Peter Rolf [this message]
2011-05-27 11:57 ` Peter Rolf
2011-05-27 13:09 ` Hartmut Henkel
2011-05-27 15:11 ` Peter Rolf
2011-05-27 15:19 ` luigi scarso
2011-05-27 15:34 ` Peter Rolf
2011-05-25 14:40 ` Hans Hagen
2011-05-26 17:32 ` mathew
2011-05-26 17:43 ` mathew
2011-05-27 6:17 ` Henning Hraban Ramm
2011-05-27 7:43 ` Hans Hagen
2011-05-26 17:55 ` mathew
2011-05-26 17:58 ` Martin Schröder
2011-05-26 22:52 ` George N. White III
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