[Mapserver-users] Raster geotiff turns background yellow

[Mark Cave-Ayland]

Hi Randy,

I remember reading on the list that the GD v1 library used by mapserver
is limited to 256 colours - so maybe you are seeing a result of
mapserver attempting to reduce the colour depth of your image? Mapserver
3.7 uses GD v2 which may solve the problem.


Hope this helps,

Mark.


---

Mark Cave-Ayland
Webbased Ltd.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England

Tel: +44 (0)1752 764445
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> -----Original Message-----
> From: randy james [mailto:rjames57 at yahoo.com]
> Sent: 28 January 2003 18:37
> To: Mapserver Users
> Subject: RE: [Mapserver-users] Raster geotiff turns background yellow
> 
> Hi List
> 
> Well i am still having the problem of a projected
> geotiff file changing the output of the mapserver cgi:
> the background turns yellow.
> 
> I've tried
> 
>  importing and than exporting the image through GRASS
> 
>  tiff2bw to ensure the file is grayscale
> 
>  upgraded to the remotesensing site version of GDAL
> 1.1.7.1 from the Mandrake 8.2 version of 1.1.7.
> 
> The geotiff image seems to be exactly like the ones
> that do not cause the problem.
> 
> i am including a couple of files from the tmp
> directory, one where the background is yellow and one
> where it is not.
> 
> does anyone know what next i should check?
> 
> --- Ed McNierney <ed at topozone.com> wrote:
> > Randy -
> >
> > Is it possible for you to make the GeoTIFF
> > available?  Thanks.
> >
> > 	- Ed
> >
> > Ed McNierney
> > President and Chief Mapmaker
> > TopoZone.com / Maps a la carte, Inc.
> > 73 Princeton Street, Suite 305
> > North Chelmsford, MA  01863
> > ed at topozone.com
> > (978) 251-4242
> >
> > -----Original Message-----
> > From: randy james [mailto:rjames57 at yahoo.com]
> > Sent: Monday, January 27, 2003 12:35 PM
> > To: Mapserver Users
> > Subject: Re: [Mapserver-users] Raster geotiff turns
> > background yellow
> >
> >
> > Hi List
> >
> > I checked the geotiff file in the GIMP and it did
> > not
> > have any yellow in the image. But than i checked the
> > image created by Mapserver and it has the yellow
> > background on it. Soo i assume that the cgi is
> > creating the yellow. Also i noticed that the polygon
> > layer loaded before the geotiff has changed to the
> > grayscale color of the geotiff.
> >
> > I am sending the rendered imaged created by
> > mapserver
> > cgi for review.
> >
> > Cheers
> > Randy
> >
> > --- woodbri at swoodbridge.com wrote:
> > > Randy,
> > >
> > > I assume that the color change is taking place
> > when
> > > view in a
> > > browser? Have you tried to view it in an image
> > > viewer?
> > >
> > > Sometimes the browser pre allocates an bunch of
> > > colors and when you
> > > load the geotiff, it does not have enough slots in
> > > the color lookup
> > > table and has to assign the additional colors to
> > > existing ones. Some
> > > software is better at this than others, but it is
> > > typically the
> > > reason why your get the type of color change you
> > > described.
> > >
> > > -Steve W.
> > >
> > > On 24 Jan 2003 at 14:51, randy james wrote:
> > >
> > > > Hi list
> > > >
> > > > Has anyone experienced problems with a geotiff
> > > file
> > > > making the image background turn yellow? (or any
> > > > color)
> > > >
> > > > The orthophoto (geotiff) that causes the problem
> > > is my
> > > > fist attempt at projecting a raster on the fly.
> > I
> > > have
> > > > tried importing the ortho into GRASS and than
> > > > exporting it again, but it did not make a
> > > difference.
> > > >
> > > > The gdalinfo utility output is quite large for
> > the
> > > > ortho causing the problem, but once its exported
> > > from
> > > > GRASS it is the same as the orthos that work (i
> > > think)
> > > >
> > > > I'm wondering if its something to to with
> > > projecting a
> > > >  raster or is it the file format. I will read
> > and
> > > try
> > > > the gdal_translate utility next i guess
> > > >
> > > > MapServer version 3.6.4 OUTPUT=PNG OUTPUT=JPEG
> > > > OUTPUT=WBMP SUPPORTS=PROJ SUPPORTS=TTF
> > > > SUPPORTS=WMS_SERVER INPUT EPPL7 INPUT=JPEG
> > > > INPUT=POSTGIS INPUT=GDAL INPUT=SHAPEFILE
> > > >
> > > > Cheers
> > > > Randy
> > > >
> > > >
> > > >
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