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I have raster from Landsat 4 that I have created a symbology for. I want to save the new raster and to keep the NDVI values, but whenever I save the raster I lose the NDVI values.

enter image description here

On the left side you can see the values I get from the raster. I have saved band 4 which is supposed to be NDVI. But now it does not show the correct values anymore.

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  • What if you specify output mode as Raw data instead of Rendered image?
    – Ben W
    Oct 20, 2019 at 7:28
  • Then I lose my symbology
    – ReutKeller
    Oct 20, 2019 at 7:31
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    I think you should export your image as Raw Data, you should also export your symbology and apply it again to your exported raster. Oct 20, 2019 at 8:03
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    You say that "you lose the ... values", but that is confusing. After export, what DO you get for band 4? NoData? Zero? No band 4 at all? Or is it that the exported band 4 data values are present and correct, but your color symbology is lost?
    – Stu Smith
    Oct 20, 2019 at 16:38

2 Answers 2

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When saving rasters, I've never paid attention to the Rendered image option in Output mode, so I can't speak to it.

However, here's my go-to workflow for saving rasters where I want to preserve symbology:

  1. In the source raster, set the symbology to your liking. Then double-click the raster in the Table of Contents, which opens the Layer Properties window. At the bottom of that window, click the Style button and select Save style..., which allows you to save the symbology as a QGIS style file, with the extension .qml.

  2. Export > Save As... the source raster to the output raster, using Output Mode > Raw Data.

  3. Then load the newly-created output raster and double-click it in the Table of Contents, which opens up the Layer Properties window. At the bottom of that window, click the Style button and select Load style.... Select the previously saved .qml file, and Voila! your output raster utilizes the same style as the source raster.

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You lost your symbology because qgis save it as RGB values where they are set accordingly to your symbology in the Layer. And no other way is possible. You can save as RAW data, and you will have values that you want, but need some software to style it, or save it as rendered image, where is its only image with color depends on your symbology.

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