Thanks Chaitanya, i forgot to add, that I was refering to an option in gdalbuildvrt, there is no way of specifying expansion there ? (otherwise, there is a lot of manual work to do in the XML)
Let me know if I am wrong ! I solved my problem by 1) Creating a VRT on the original RGB tiles 2) Creating a 20% size "sample.tif" RGB tiff from the VRT 3) running rgp2pct on sample.tif 4) running a new rgb2pct on all the tiles, using the result from 3) as -pct option That way I get the same colour table on all tiles, and it looks acceptable. - oyvind On Wed, Apr 11, 2012 at 10:55 AM, Chaitanya kumar CH <[email protected] > wrote: > Oyvind, > > VRT does support colortable expansion. > Check out the ComplexSource sub-topic in the vrt doc page[1]. >> >> From the The ComplexSource supports fetching a color component from a >> source raster band that has a color table. The ColorTableComponent value is >> the index of the color component to extract : 1 for the red band, 2 for the >> green band, 3 for the blue band or 4 for the alpha band. >> > > [1]: http://www.gdal.org/gdal_vrttut.html > > On Wed, Apr 11, 2012 at 1:27 PM, Oyvind Idland <[email protected]>wrote: > >> Hello, >> >> I am fiddling with some old scanned (handmade) maps. In order to reduce >> the size of the data, and since >> the maps has a limited amount of colors, i figured that using palettized >> 8BPP tiffs would be suitable in this >> case. >> >> I got several tiles that make up the whole area, using rgb(0,0,0) as >> nodata (making JPEG compression >> unsuitable) >> >> The idea was to use VRT to join these together, but since they all have >> different color tables, >> this is not possible. >> >> Would it be an idea to implement support for an "expand option" in VRT, >> e.g expanding to rgb/rgba ? >> >> Not sure how many would need this feature though. >> >> >> -- oyvind >> >> _______________________________________________ >> gdal-dev mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/gdal-dev >> > > > > -- > Best regards, > Chaitanya kumar CH. > > +91-9494447584 > 17.2416N 80.1426E >
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