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<p>Hey Richard,</p>
<p>do you have different NODATA pixels between the three bands (R,
G, B) or is it the same? If there are no differences then you can
use an additional channel as mask. I would suggest you store your
imagery in GeoTIFF with an "internal mask". Even posted a nice
example of this in
<a class="moz-txt-link-freetext" href="https://lists.osgeo.org/pipermail/gdal-dev/2014-August/039907.html">https://lists.osgeo.org/pipermail/gdal-dev/2014-August/039907.html</a><br>
If your format supports RGBA (e.g. PNG), then that would be
another way to achieve this but a nice GeoTIFF should be the best
solution.</p>
<p><br>
Cheers, Hannes<br>
</p>
<div class="moz-cite-prefix">Am 13.01.22 um 18:35 schrieb Richard
McDonnell:<br>
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<p class="MsoNormal">Hi all,<o:p></o:p></p>
<p class="MsoNormal">I have a general GIS query and am hoping I
can get some insight from the community.<o:p></o:p></p>
<p class="MsoNormal">It relates to how we deal with pixels with
no data in RGB Imagery. It seems to be typical to produce RGB
imagery as 8bit with pixel values between 0 and 255, with
either 0 or 255 being used as the NoDATA value. To me this is
problematic, as there can be valid pixels within your image
with 0 or 255. To me the solution is to use 16bit Imagery and
to assign the NoDATA value to any value outside of the 0 – 255
range.<o:p></o:p></p>
<p class="MsoNormal">I know in DEM’s its usual to use -9999 as
your NoDATA value but my question is, Is there a standardised
way to deal with NoDATA in RGB?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I welcome any comments and suggestions.<o:p></o:p></p>
<p class="MsoNormal">Regards & Thanks in advance,<o:p></o:p></p>
<p class="MsoNormal"><br>
Richard.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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——</span><br>
<span style="FONT-FAMILY: Arial, sans-serif; FONT-WEIGHT:
bold; COLOR: #004d44">Richard McDonnell MSc GIS, FME
Certified Professional</span><br>
<span style="FONT-FAMILY: Arial, sans-serif; COLOR:
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<br>
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<span style="FONT-FAMILY: Arial, sans-serif; COLOR:
#565148">——</span><br>
<span style="FONT-FAMILY: Arial, sans-serif; COLOR:
#565148">M +353 87 688 5964 T +353 46 942 2409</span><br>
<a href="https://gov.ie/opw" moz-do-not-send="true">https://gov.ie/opw</a><br>
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<span style="FONT-FAMILY: Arial, sans-serif; COLOR:
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below
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