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I georeferenced a raster file and ended up with black background (exact 000000) The raster file contains a lot of blacks, so setting black to be a transparent color is not a good solution since I would lose the details on the raster file.

I have seen several similar questions from a few years ago. None of the answers is straightforward and works in my case. Hoping there is a better solution in more recent QGIS versions.

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For me the best method is to edit the file in Photoshop (or other editor). Double click on background layer and make it a general layer. Then I select the one pixel in the right lower corner and delete this pixel, it will turn transparent. Then I save the file as TIFF with zip-compression, no layers with transparency on. Then when you Georeference the borders will be transparent.

save in photoshop

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Thank you Michael, this answered helped

Here are the detailled steps I took. If someone is not an export in QGIS, it might help.

  • Upload raster in QGIS
  • Apply relevant CRS
  • Add transparent no data value to raster (e.g. -333333)
  • Save as Geotiff
  • Open the Geotiff in the Georeferencer (Do not check use 0 for transparency)
  • In raster properties (add no value e.g. -333333) -Run the georeferencer and you should end up with clean file with a transparent background instead of the black background

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