[GRASS5] r.in.png/r.out.png

Andreas Lange Andreas.Lange at Rhein-Main.de
Wed Nov 22 18:28:36 EST 2000


Hi Eric,

thanks for the hint. I'll look into that another time and update the
code of r.in.png and r.out.png. 
The pnm.h header includes internally half a dozen other header files,
and in one older version one header that is incompatible with some
Cygwin header. 
But i can compile r.in.png and r.out.png now on Linux, IRIX and
Cygnus/Win32.

As a side note: GDAL supports non-georeferenced image formats (jpeg,
png) too, so that i think we should standardize on GDAL in the long
term. The complicated part with image import is IMHO not reading/writing
the image, but the color support for GRASS. And that is not appropriate
with r.in.png/r.out.png.

cu,

Andreas

Eric G . Miller wrote:
> 
> Haven't looked myself, but does the code specify a compression level
> and/or bit packing for the png_lib?  Deflate compression (zlib) should
> be built in and only needs to be specified at the beginning with a call
> like:
>         png_set_compression_level (png_ptr, Z_DEFAULT_COMPRESSION);
> 
> I just gleaned this from the libpng.txt file that came with the library
> (I'd hardly claim to be an expert).
> 
> I'll be adding zlib.h/libz checks to the configure script and it will
> define HAVE_ZLIB_H in src/include/config.h.  Actually, I already did
> this and then found how the configure script has things *not* in
> configure.in (Oooh, bad).  Ahh, I see zlib.h is already included in png.h.
> Still, configure should check.
> 
> --
> Eric G. Miller <egm2 at jps.net>
> 
> ----------------------------------------
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-- 
Andreas Lange, 65187 Wiesbaden, Germany, Tel. +49 611 807850
Andreas.Lange at Rhein-Main.de - A.C.Lange at GMX.net



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