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Help me for processing my raster data on QGIS;

  1. How to remove the outland on my image, so the image is following my shapefile border

  2. why is my processing using "Clip With Mask" in QGIS for so long, about 30 minutes? But not on My ArcMap.

  • Raster images are rectangles. There will always be black areas, if you image content is not rectangular.
    – Erik
    Sep 20, 2019 at 8:18
  • 1
    When doing Clip by Mask in QGIS, there is an option to write a value under the Assign nodata value, write -9999. When the process finishes, the black color will not be visible. However, the image extent will no be changed, as @Erik said, the image always rectangular shape
    – ahmadhanb
    Sep 20, 2019 at 8:48
  • Or you can assign transparency to all black (0,0,0) pixels via the layer properties.
    – Erik
    Sep 20, 2019 at 8:50
  • Thankyou So much guys Sep 21, 2019 at 0:02

2 Answers 2


I think you can find the answer on this link -


"The border value, which is currently black, may be set to NoData using the RasterBandNoDataSetter transformer with a noData value set to 0. This will result in the background becoming transparent. If done this way, there is the possibility that a pixel exists in the imagery (valid data range) that is actually set to 0 for all of the bands (matching the background). Setting 0 to NoData will set cells with this value to transparent which would generally be undesirable for valid data.

Note that for ‘numeric’ data, it makes more sense to use NoData because it’s likely that you can pick a value that does NOT exist in the imagery."

There are several ways explained on how you could remove black background from the raster.


Using no data value -9999 the black background was removed. Thank you for the help.


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