[gdal-dev] Modify original ColorTable in VRT & TIFF files

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Hi all,

I'm looking to modify the original ColorTable, when georeferencing, PNG => gdal_translate + gdalwarp => TIFF.

> gdal_translate -of VRT -a_srs EPSG:4326 file_png file_vrt -a_ullr xxxx
> gdalwarp -s_srs EPSG:4326 -t_srs EPSG:3857 file_vrt file_tiff

If I open the VRT file and do the edit manually, the output TIFF file is correct.
The problem is that I have 524288 files ... so I would like to do the modification automatically, via gdal_translate.
But I don't quite understand using the parameters of the command ...

• Original VRT & TIFF files

# VRT
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Palette</ColorInterp>
    <ColorTable>
      <Entry c1="0" c2="0" c3="255" c4="255" />
      <Entry c1="255" c2="255" c3="255" c4="255" />
      <Entry c1="0" c2="0" c3="0" c4="255" />
        [...]
      <Entry c1="0" c2="0" c3="0" c4="255" />
    </ColorTable>
  </VRTRasterBand>

# TIFF
  Band 1 Block=63153x1 Type=Byte, ColorInterp=Palette
  Color Table (RGB with 256 entries)
    0: 0,0,0,255
    1: 255,255,255,255
    2: 0,0,0,255
      [...]
  255: 0,0,0,255


I want this :
• Modified VRT and TIFF files

# VRT
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Palette</ColorInterp>
    <ColorTable>
      <Entry c1="0" c2="0" c3="255" c4="255" />
      <Entry c1="0" c2="255" c3="0" c4="255" />
      <Entry c1="255" c2="0" c3="0" c4="255" />
        [...]
      <Entry c1="255" c2="0" c3="0" c4="255" />
    </ColorTable>
  </VRTRasterBand>

# TIFF
  Band 1 Block=63153x1 Type=Byte, ColorInterp=Palette
  Color Table (RGB with 256 entries)
    0: 0,0,255,255
    1: 0,255,0,255
    2: 255,0,0,255
      [...]
  255: 255,0,0,255

Whatever I find, redirects me to gdaldem (which I can't use). In gdal_translate, it seems to me that the parameter -colorinterp_X might be suitable
but I can't find any concrete examples (or I have not looked in the right place).

I want to impose the following parameters:
Band 1
Type = Byte
ColorInterp = Palette
Color Table (RGB with 256 entries)

In ColorTable:
Entry 0 = 0,0,255,255
Entry 1 = 0,255,0,255
Entries 2 to 255 = 255,0,0,255