[NTG-pdftex] Expanded png inclusion support

The Thanh Han hanthethanh at myrealbox.com
Sat Jan 29 01:39:16 CET 2005


Hi,

is anyone doing something with Taco's patch? If not I will merge it to
pdftex sources (will be uploaded soon as 1.20c-beta<date>

Thanh



On Tue, Jan 11, 2005 at 05:29:39PM +0100, Taco Hoekwater wrote:
> 
> Hi,
> 
> This is a complete, working patch, but the zip only contains the actual 
> pngextra.ch and replacement writepng.c, so some manual editting has to 
> be done to the Makefile. The change file needs to be added as the last
> item of the "pdftex_web_srcs" collection, the C file can overwrite the
> current file.
> 
> This version is for testing purposes. I can provide linux 2.6 binaries,
> but I don't know how to create win32 executables, sorry.
> 
> The main part of the patch is the new writepng.c, but there is also
> some web glue to set defaults. The patch contains improvements for PNG
> image inclusion, specifically:
> 
> - alpha channel and transparency (only if %!PDF >=1.4)
> - 16-bit colour (only if %!PDF >=1.5)
> - gamma correction
> - forced reduction to greyscale (for Hans)
> 
> A few primitives had to be introduced to set some default values.
> There are a total of four new primitives, that are all integer 
> parameters. I almost certainly made mistakes in the WEB coding
> (initialization locations etc.), but works well enough for testing.
> 
> Here are  the primitives and their defaults:
> 
>   \pdfoptionpdfimagehicolor = 1
>   %
>   % can be set to 0 if undesirable. This is perhaps needed because
>   % the reader 5 will reject the pdf document's page completely
>   % otherwise.
> 
>   \pdfimagegamma = 2200
>   %
>   % if not supplied in the image. This example implies that the image
>   % was originally created with gamma value 2.2 (like magnification)
> 
> 
>   \pdfgamma = 1000
>   %
>   % Gamma value for the 'pdf device'. It looks like this is the
>   % 'correct' value used by Adobe, but I'm not 100% sure.
> 
>   \pdfoptionimageforcegray = 0
>   %
>   % If 1, all included PNGs are written to the pdf as greyscale.
> 
> The problem with these primitives is that I am unsure how and
> when to convert the internal parameters into their C 'fixedxxxxxx'
> counterparts. It would be a lot cleaner if the C code would use
> the internal parameters directly, but I'm not sure if that is
> even possible. Help needed!
> 
> 
> Greetings, Taco
> 
> noreply at sarovar.org wrote:
> >Patches item #259, was opened at 2005-01-11 16:44
> >
> >Submitted By: Taco Hoekwater (taco)
> >Summary: Expanded png inclusion support
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