[gdal-dev] Re: 254 into 255

[Chaitanya kumar CH]

J,

A vrt file[1] can implement your requirements. It can create a 'lookup
table' to translate your pixel values.
Start by running gdalbuildvrt on your raster file and modify it to contain
the LUT element. It will look something like this:

<VRTDataset rasterXSize="512" rasterYSize="512">
  <VRTRasterBand dataType="Byte" band="1">
    <ComplexSource>
      <SourceFilename relativeToVRT="1">utm.tif</SourceFilename>
      <SourceBand>1</SourceBand>
      <ScaleOffset>0</ScaleOffset>
      <ScaleRatio>1</ScaleRatio>
      <LUT>0:0,253:253,254:255</LUT>
      <SrcRect xOff="0" yOff="0" xSize="512" ySize="512"/>
      <DstRect xOff="0" yOff="0" xSize="512" ySize="512"/>
    </ComplexSource>
  </VRTRasterBand>
  <VRTRasterBand dataType="Byte" band="2">
    <ComplexSource>
      <SourceFilename relativeToVRT="1">utm.tif</SourceFilename>
      <SourceBand>2</SourceBand>
      <ScaleOffset>0</ScaleOffset>
      <ScaleRatio>1</ScaleRatio>
      <LUT>0:0,253:253,254:255</LUT>
      <SrcRect xOff="0" yOff="0" xSize="512" ySize="512"/>
      <DstRect xOff="0" yOff="0" xSize="512" ySize="512"/>
    </ComplexSource>
  </VRTRasterBand>
  <VRTRasterBand dataType="Byte" band="3">
    <ComplexSource>
      <SourceFilename relativeToVRT="1">utm.tif</SourceFilename>
      <SourceBand>3</SourceBand>
      <ScaleOffset>0</ScaleOffset>
      <ScaleRatio>1</ScaleRatio>
      <LUT>0:0,253:253,254:255</LUT>
      <SrcRect xOff="0" yOff="0" xSize="512" ySize="512"/>
      <DstRect xOff="0" yOff="0" xSize="512" ySize="512"/>
    </ComplexSource>
  </VRTRasterBand>
</VRTDataset>


The LUT element is the key here. It tells the VRT driver to keep the values
from 0 to 253 as they are and change 254 to 255.
Remember to replace the appropriate parts.

[1]: http://www.gdal.org/gdal_vrttut.html

On Thu, Oct 27, 2011 at 12:40 PM, joolek <joolek.o at gmail.com> wrote:

> Yes, this is exactly what I am struggling to do. Gdal is so powerful - but
> I can't get it working.
> J
>
>
> On 26 Oct 2011, at 17:10, "Chaitanya kumar CH [via OSGeo.org]"<[hidden
> email] <http://user/SendEmail.jtp?type=node&node=6935299&i=0>> wrote:
>
> Do you want to convert just the pixels with the values (254,254,254)?
>
> On Wed, Oct 26, 2011 at 9:33 PM, joolek <[hidden email]<http://user/SendEmail.jtp?type=node&node=6933215&i=0>
> > wrote:
>
>> Hi I basically want to convert all the 254 254 254 into 255 255 255... is
>> this possible?
>>
>> --
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>
>
>
> --
> Best regards,
> Chaitanya kumar CH.
>
> +91-9494447584
> 17.2416N 80.1426E
>
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-- 
Best regards,
Chaitanya kumar CH.

+91-9494447584
17.2416N 80.1426E
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