[Gdal-dev] gdalwarp changes colortable

[acangi]

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acangi wrote:
> 
> Hello,
> 
> I try to translate colormapped geotiff files from EPSG:31300 to EPSG:3812,
> using 
> 
> $ gdalwarp -s_srs EPSG:31300 -t_srs "+proj=lcc +lat_1=49.83333333333334
> +lat_2=51.16666666666666 +lat_0=50.79781500000000 +lon_0=4.359215833333335
> +x_0=649328.0 +y_0=665262.0 +ellps=intl +units=m +no_defs" top250r.tif
> top250r_warp.tif
> 
> Using -t_srs EPSG:3812 gives a "is this a valid coordinate system ?"
> Using -t_srs 3812.prj (file containing the WKT, taken from 
> http://spatialreference.org/ref/epsg/3812/ogcwkt/
> http://spatialreference.org/ ) gives a "No translation for Lambert Conic
> Conformal (2SP) to PROJ.4 is known"
> As I couldn't find the PROJ.4 syntax for this SRS, I built it based on
> data from the WKT.
> 
> Coordinates transformation seems to work fine, but my colors are wrong:
> 
> 
> Before :  http://n2.nabble.com/file/n2334758/before.jpeg                
> After :  http://n2.nabble.com/file/n2334758/after.jpeg 
> 
> Checking the files with gdalinfo, I see differences :
> 
> Size is 18300, 15000 ==> Size is 18301, 15001
> The projection, the origin and the corner coordinates change like expected
> Pixel Size = (16.666670000000000,-16.666699999999999) ==> Pixel Size =
> (16.666302967680906,-16.666302967680906)
> Metadata:
>   AREA_OR_POINT=Area
>  
> TIFFTAG_DOCUMENTNAME=\\backstage\jobcontainer1\symb\map250\tiff\plot_complet.tif
>   TIFFTAG_SOFTWARE=Barco Graphics TIFFOut V1.0.2
>   TIFFTAG_XRESOLUTION=381
>   TIFFTAG_YRESOLUTION=381
>   TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
> ==> Metadata:
>   AREA_OR_POINT=Area
> Image Structure Metadata:COMPRESSION=LZW  INTERLEAVE=BAND ==> Image
> Structure Metadata: INTERLEAVE=BAND
> Band 1 Block=256x256 Type=Byte, ColorInterp=Palette ==> Band 1
> Block=18301x1 Type=Byte, ColorInterp=Palette
> The color table is the same.
> 
> I tried with some more options : -of GTiff -co "PROFILE=GeoTIFF" -co
> "INTERLEAVE=PIXEL" -co "COMPRESS=LZW" -co "TILED=YES" :
> Size is 18300, 15001
> Yet another Pixel Size
> I get the "COMPRESSION=LZW"
> and Band 1 Block=256x256 Type=Byte, ColorInterp=Palette
> 
> ...but the colors are still wrong.
> 
> Any idea how I can change the projection without affecting the colors ?
> 
> 

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