Setting pixel value from 0 to 10

Question

How can I change the pixel value from 0 to 10 on QGIS?

If you would like to change all zeros to ten in your raster then you can use raster calculator. To change a single pixel value you need gimp or similar image manipulation program. — Zoltan, Feb 22 at 10:14
I would like to change all 0 values to 10. How can I write this into the Raster Calculator? Thank you very much — Leonardo, Feb 22 at 10:20
Please try ("YourRaster@1" = 0) * 10 + ("YourRaster@1" != 0) * ("YourRaster@1") — Kazuhito, Feb 22 at 11:02

Kazuhito · Accepted Answer · 2021-02-22 21:28:41Z

Allow me to rephrase the question "change the pixel value from 0 to 10" as follows;

(1) The first one is expressed as ("YourRaster@1" = 0) * 10.

(A) when the pixel value is 0, condition ("YourRaster@1" = 0) returns True which is 1. Then 1 * 10 becomes 10.
(B) when the pixel value is not 0, condition ("YourRaster@1" = 0) returns False which is 0. Then 0 * 10 becomes 0.

(2) The second one is expressed as ("YourRaster@1" != 0) * ("YourRaster@1").

(C) when the pixel value is 0, condition ("YourRaster@1" != 0) returns False. Then 0 * ("YourRaster@1") becomes 0.
(D) when the pixel value is not 0, condition ("YourRaster@1" != 0) returns True. Then 1 * ("YourRaster@1") becomes ("YourRaster@1") (i.e. your original pixel value).

(3) Finally, by putting these two together, ("YourRaster@1" = 0) * 10 + ("YourRaster@1" != 0) * ("YourRaster@1") will work this way:

When the pixel value is 0, (A) + (C) becomes 10 + 0, which is 10.
When the pixel value is not 0, (B) + (D) becomes 0 + "YourRaster@1", which is the pixel value of your original raster.

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