Swapping raster bands

Computer displays render images in the visible spectrum of red, green, and blue light (RGB). However, raster images may contain bands outside the visible spectrum. Such rasters make poor visualizations, so you will often want to recombine the bands to change the RGB values.

Getting ready

For this recipe, we will use a false-color image, which you can download from https://github.com/GeospatialPython/Learn/raw/master/FalseColor.zip.

Unzip this .tif file and place it in your /qgis_data/rasters directory.

How to do it...

We will load this raster and swap the order of the first and second bands. Then, we will add it to the map. To do this, we need to perform the following steps:

1. Start QGIS.

2. From the Plugins menu, select Python Console.

3. In the Python console, load the layer and ensure that it is valid:

           rasterLyr = QgsRasterLayer("/qgis_data/rasters/FalseColor.tif",
                                      "Band Swap") 
           rasterLyr.isValid() 
   

4. Now, we must access the layer...