[Gdal-dev] gdalwarp changes colortable

[Chaitanya kumar CH]

acangi,

Could you check if the after image shows any different colors with
some other image viewer like ImageMagick? OpenEV might not be reading
the color table correctly.

-- 
Chaitanya kumar CH.

On Mon, Feb 16, 2009 at 7:43 PM, acangi <aca at ngi.be> wrote:
>
> Subscription problem, reposting as requested.
>
>
> 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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