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<p class="MsoNormal"><span style="font-size:11.0pt">Hmm, good catch. Looking at the stats for the red band:<br>
<br>
Band 1 Block=128x128 Type=UInt16, ColorInterp=Gray<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> Min=130.000 Max=36265.000 <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> Minimum=130.000, Maximum=36265.000, Mean=10415.962, StdDev=3502.933<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> NoData Value=0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> Metadata:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> STATISTICS_MAXIMUM=36265<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> STATISTICS_MEAN=10415.961859513<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> STATISTICS_MINIMUM=130<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> STATISTICS_STDDEV=3502.9325925887<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> STATISTICS_VALID_PERCENT=49<br>
<br>
So, is there no way to actually do this via command line, or am I going to have to write a python lib to actually read through these and determine what they should be scaled to?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Daniel Evans <daniel.fred.evans@gmail.com>
<br>
<b>Sent:</b> Monday, April 22, 2024 9:29 AM<br>
<b>To:</b> Raley, Nathan <nraley@gaig.com><br>
<b>Cc:</b> 'gdal-dev@lists.osgeo.org' (gdal-dev@lists.osgeo.org) <gdal-dev@lists.osgeo.org><br>
<b>Subject:</b> [External] Re: [gdal-dev] Question on building multi band composite and going back to RGB GeoTiff<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-line-height-alt:.75pt"><span style="font-size:1.0pt;color:white">Hi Nathan, My initial suspicion might just be that the scaling the data provider did to go from the raw data to a human-eye-friendly RGB composite isn't the conversion
you're assuming. I know that with the data I regularly work with, <o:p></o:p></span></p>
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<p class="MsoNormal">Hi Nathan,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">My initial suspicion might just be that the scaling the data provider did to go from the raw data to a human-eye-friendly RGB composite isn't the conversion you're assuming.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I know that with the data I regularly work with, it may be provided as Uint16, but the data range doesn't extend all the way to 65535.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If you compare the values in the separate R and G images to the RGB composite, do they appear to match the conversion you're assuming, or is there a different scaling (and possibly offset)?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Cheers,<o:p></o:p></p>
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<p class="MsoNormal">Daniel<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Mon, 22 Apr 2024, 15:20 Raley, Nathan via gdal-dev, <<a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I currently have a RGB geotiff composite image that has a Byte datatype. I also have individual band images for R, G, Redge, and NIR that are UInt16 datatypes. Since I’m missing
the Blue band from the individual bands, I was attempting to extract the blue band from the RGB composite image, scale it up to the UInt16 datatype, and build a composite VRT with R, G, B, NIR, RE bands included in it. I was then attempting to extract the
RGB bands from the multispec VRT in order to see if the process was working as intended, but I’m getting an extremely blue image.<br>
<br>
Can anyone shed some light as to what I may be doing wrong here?<br>
<br>
I started by building a VRT for each band:<o:p></o:p></p>
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gdal_translate source_RGB.tif b.vrt -ot UInt16 -of VRT -b 3 -scale 0 255 0 65535 <o:p>
</o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
gdalbuildvrt -b 1 r.vrt source_R.tif<br>
gdalbuildvrt -b 1 g.vrt source_G.tif<br>
gdalbuildvrt -b 1 nir.vrt source_NIR.tif<br>
gdalbuildvrt -b 1 re.vrt source_RE.tif<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I then merged the VRTs:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
gdalbuildvrt -separate multispec.vrt r.vrt g.vrt b.vrt nir.vrt re.vrt<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I now have a multispec.vrt with the R, G, B, NIR, and RE bands, all with a UInt16 datatype.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Now, I attempted to rebuild a RGB GeoTiff from the composite VRT with something like:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
gdal_translate -ot Byte -of GTiff -b 1 -b 2 -b 3 -scale 0 65535 0 255 -co PHOTOMETRIC=RGB multispec.vrt multispec.tif<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Viewing the result in QGIS appears overly blue. What am I doing wrong here?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Nathan
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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