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I'm hoping to deal with this using the raster calculator in QGIS. But, here's my issue (and I'm a pretty novice GIS user); when you bring a raster image into MI, it turns all the null ("no data") values to white. In MapInfo, to make those previously null values transparent, I have to select that white color as the target color for transparency. But that makes any pure whites (typically over exposed images) also transparent.

Before enter image description here

After enter image description here

My thought was, prior to bringing the raster into MI, to use the raster calc in QGIS to alter the pixel values for these whites (255 in all four bands) to something like 254. Not sure how exactly to do that, though, or if it will work well, or if there is an easier way. I searched endlessly before posting.

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  • You have a good plan. You can also use gdal_calc.py gdal.org/gdal_calc.html.
    – user30184
    Jun 15, 2018 at 15:07
  • I need help pulling that off in the calc. The gdal_calc looks even more advanced.
    – Jessie
    Jun 15, 2018 at 15:36
  • I used the calc on all four bands like this but now I have four separate band tif's and not sure how to put them back together of if this is even the best approach. "HolcombSouth_Orthomosaic_export_TueJun12@1" - 1
    – Jessie
    Jun 15, 2018 at 17:01
  • The GDAL raster merge tool will merge single band rasters into one multiband image. wiki.awf.forst.uni-goettingen.de/wiki/index.php/…
    – csk
    Jun 18, 2018 at 18:30
  • None of this is working for me, likely due to my lack of skills. How do I change no data values without exporting into individual bands? (idiot proof, please)
    – Jessie
    Jun 19, 2018 at 18:34

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