[mapserver-users] a question about tiffimages

[Chris Stuber]

Frank,

Are you saying... that GDAL 3.5 can project 
and resample a TIFF raster?  VERY COOL if it does.
Is the tiff support replacement capable of dealing with
a 24-bit TIFF, cause I don't think that libtiff will.

Yep, the new versions of GD (2.0 and 2.01) support the TrueColor 
alpha channel/transparent blending, CopyResampled (copy
with resampling), and TrueColorToPalette functions.  Supports
only JPG, PNG and WBMP formats...  It would be nice if mapserver
were capable of producing 24-bit images... alot more could be
done with anti-aliasing with Truecolor.

I preprocess my rasters with Adobe Illustrator or PaintShop Pro...
Typically, I have to convert my 24-bit images to 8-bit (if they are
not 8-bit already) and 2) decrease the image colors to around 150
to 200 colors.  Sometime I still have trouble with filling up
the color table with colors defined in my mapfile and or symbols
which are pixmaps (gifs) that may contain a handful of colors.
It would be great to have a tools capable preprocessing these
rasters... using a GUI to do it, isnt much fun.

Regards,

Chris Stuber (mapsurfer)



Frank Warmerdam wrote:
> 
> Stephen Lime wrote:
> > On the 24-bit side, a new version of GD is out. It will be integrated after the initial
> > 3.5 release. It's unclear how useful it will be though. It definitely reads (writes?)
> > truecolor but it's gotta be slower so integration may be tricky especially when
> > preserving GIF support.
> 
> Steve, et al,
> 
> Does anyone know if the new gd supports png alpha output?  For WMS purposes
> it would be ideal to treat output with some transparent portions via
> an alpha value for each pixel rather than just the current approach of setting
> aside one palette value as transparent.
> 
> > Note: there may be functionality in the new 3.5 GDAL support that replaces
> > current TIFF support if compiled in. In know there's projection and resampling
> > code in place but don't know if there's any color quantization code as well. Probably
> > doesn't matter since there's still only 8-bit output.
> 
> There are algorithms in GDAL for colour quantization but they aren't directly
> used by MapServer.  It seems to me that this sort of thing should be
> done as a preprocessing stage before putting up data for use with MapServer.
> Right?  What do people use for preprocessing their raster images into
> paletted form?  Is there interest in my providing some preparation tools
> for applying image enhancements, and doing colour quantization with
> detailed control?  I have these in rough form already as part of GDAL.
> 
> Best regards,
> 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent