[gdal-dev] vrt removes transparent pixels?

[Wendell Turner]

On Wed, Apr 07, 2010 at 01:59:35AM +0530, Chaitanya kumar CH wrote:
> Wendell,
> 
> Can you provide the exact commands you used?

  wget http://radar.weather.gov/ridge/Conus/RadarImg/centgrtlakes_radaronly.gif
  gdal_translate -of VRT centgrtlakes_radaronly.gif foo.vrt
  cp centgrtlakes_radaronly.gif test.gif
  gdal_translate foo.vrt test.gif

  gimp centgrtlakes_radaronly.gif test.gif

Also, I notice that the test.gif file is about ten times the
size of the original one.

Thanks,

Wendell

> On Wed, Apr 7, 2010 at 12:52 AM, Wendell Turner <wendell at enflight.com>wrote:
> 
> > I want to change the color palette on a gif file.  The
> > instructions on the wiki here:
> >
> > http://trac.osgeo.org/gdal/wiki/FAQRaster#Howtocreateormodifyanimagecolortable
> > explain how to do it:
> >  gdal_translate -of VRT your.tif your.vrt
> >  gdal_translate your.vrt your_fixedup.tif
> >
> > but doing this (without editing the .vrt file) changes
> > transparent pixels to white.  Is there a way to use
> > gdal_translate to do this and also keep transparent pixels?
> >
> > Or is that related to error message from gimp?
> >  .gif: unknown field with tag 42113 (0xa481) encountered
> > (gimp didn't complain about the original image)