J,<br><br>A vrt file[1] can implement your requirements. It can create a 'lookup table' to translate your pixel values.<br>Start by running gdalbuildvrt on your raster file and modify it to contain the LUT element. It will look something like this:<br>
<pre class="fragment"><VRTDataset rasterXSize=<span class="stringliteral">"512"</span> rasterYSize=<span class="stringliteral">"512"</span>><br> <VRTRasterBand dataType=<span class="stringliteral">"Byte"</span> band=<span class="stringliteral">"1"</span>><br>
<ComplexSource><br> <SourceFilename relativeToVRT=<span class="stringliteral">"1"</span>>utm.tif</SourceFilename><br> <SourceBand>1</SourceBand><br> <ScaleOffset>0</ScaleOffset><br>
<ScaleRatio>1</ScaleRatio><br> <LUT>0:0,253:253,254:255</LUT><br> <SrcRect xOff=<span class="stringliteral">"0"</span> yOff=<span class="stringliteral">"0"</span> xSize=<span class="stringliteral">"512"</span> ySize=<span class="stringliteral">"512"</span>/><br>
<DstRect xOff=<span class="stringliteral">"0"</span> yOff=<span class="stringliteral">"0"</span> xSize=<span class="stringliteral">"512"</span> ySize=<span class="stringliteral">"512"</span>/><br>
</ComplexSource><br> </VRTRasterBand><br> <VRTRasterBand dataType=<span class="stringliteral">"Byte"</span> band=<span class="stringliteral">"2"</span>><br> <ComplexSource><br>
<SourceFilename relativeToVRT=<span class="stringliteral">"1"</span>>utm.tif</SourceFilename><br> <SourceBand>2</SourceBand><br> <ScaleOffset>0</ScaleOffset><br>
<ScaleRatio>1</ScaleRatio><br> <LUT>0:0,253:253,254:255</LUT><br> <SrcRect xOff=<span class="stringliteral">"0"</span> yOff=<span class="stringliteral">"0"</span> xSize=<span class="stringliteral">"512"</span> ySize=<span class="stringliteral">"512"</span>/><br>
<DstRect xOff=<span class="stringliteral">"0"</span> yOff=<span class="stringliteral">"0"</span> xSize=<span class="stringliteral">"512"</span> ySize=<span class="stringliteral">"512"</span>/><br>
</ComplexSource><br> </VRTRasterBand><br> <VRTRasterBand dataType=<span class="stringliteral">"Byte"</span> band=<span class="stringliteral">"3"</span>><br> <ComplexSource><br>
<SourceFilename relativeToVRT=<span class="stringliteral">"1"</span>>utm.tif</SourceFilename><br> <SourceBand>3</SourceBand><br> <ScaleOffset>0</ScaleOffset><br>
<ScaleRatio>1</ScaleRatio><br> <LUT>0:0,253:253,254:255</LUT><br> <SrcRect xOff=<span class="stringliteral">"0"</span> yOff=<span class="stringliteral">"0"</span> xSize=<span class="stringliteral">"512"</span> ySize=<span class="stringliteral">"512"</span>/><br>
<DstRect xOff=<span class="stringliteral">"0"</span> yOff=<span class="stringliteral">"0"</span> xSize=<span class="stringliteral">"512"</span> ySize=<span class="stringliteral">"512"</span>/><br>
</ComplexSource><br> </VRTRasterBand><br></VRTDataset><br></pre><br>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.<br>Remember to replace the appropriate parts.<br>
<br>[1]: <a href="http://www.gdal.org/gdal_vrttut.html">http://www.gdal.org/gdal_vrttut.html</a><br><br><div class="gmail_quote">On Thu, Oct 27, 2011 at 12:40 PM, joolek <span dir="ltr"><<a href="mailto:joolek.o@gmail.com">joolek.o@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>Yes, this is exactly what I am struggling to do. Gdal is so powerful - but I can't get it working. </div>
<div>J<div class="im"><br><br>On 26 Oct 2011, at 17:10, "Chaitanya kumar CH [via <a href="http://OSGeo.org" rel="nofollow" link="external" target="_blank">OSGeo.org</a>]"<<a href="http://user/SendEmail.jtp?type=node&node=6935299&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>> wrote:<br>
<br></div></div><div></div><blockquote type="cite"><div><div class="im">
Do you want to convert just the pixels with the values (254,254,254)?<br><br></div><div class="gmail_quote"><div class="im">On Wed, Oct 26, 2011 at 9:33 PM, joolek <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=6933215&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span> wrote:<br>
</div><blockquote style="border-left: 2px solid rgb(204, 204, 204); padding: 0pt 1em;" class="gmail_quote"><div class="im">Hi I basically want to convert all the 254 254 254 into 255 255 255... is<br>
this possible?<br>
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