[mapserver-users] a question about tiffimages

[Frank Warmerdam]

Chris Stuber wrote:
> 
> 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.

Chris, 

MapServer in CVS (3.5?) with GDAL support enabled can reproject and
resample TIFF (or any other GDAL supported format).  Currently it is
slow because I do the reprojection calculation for every pixel, but I
will add polynomial approximations in the next few weeks.  With this
is should only be two or three times slower than direct processing
of the raster, and overall map generation time shouldn't be too much
higher.  

Looking through mapraster.c I don't see any drivers supporting 24bit
images (not even JPEG which seems to assume greyscale).  The current
GDAL support assumes colormapped or greyscale, much like the old
TIFF support.  I could add 24bit RGB input support, but I would 
likely have to map it to a fixed color cube since it wouldn't be
practical to do anything more intelligent on the fly.  It should be
pretty easy to use this, and this is the mechanism we used for 
8bit display of 24bit images at PCI for years with relatively good
results.  

> 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.

True, but it is a significant architectural change.  Once/if Steve is ready
for it, I would be happy to fixup the raster support to take advantage of
it. 

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