Image fusion

Pansharpening of Sentinel-2 requires defining a 10m reference band because there is no panchromatic band as for Landsat available. One option is a selection among the 10-m bands (2, 3, 4, or 8) or synthesis (e.g. weighted average of 10-m bands). Following the latter approach, luminance can be calculated from Blue, Red, Green and NIR band to receive a single band grey scale image.

Create a synthesis panchromatic band

1. Load the input image
2. Open the raster calculator and apply the following formula: Y = 0.20 * NIR 0.15 * Red + 0.58 * Green + 0.07 * Blue

1. Define path and name for the output layer
2. Click on the ‘OK-button’.

Create a pan-sharpened layer

1. Search for Pansharpening (Bayes) algorithm in the Processing Toolbox.
2. Select pseudo-panchromatic band as the Input PAN Image.
3. Select the layer stack with the original 20m bands as the InputXS Image. Therefore (1) Follow Split stack to extract the 20m Bands (additional creation parameters: :-b 5 -b 6 -b 7 -b 9 -b 11 -b 12) from the multiband file creating at the same time a new multiband file.

1. Specify the directory to save the output file and click on the ‘Run-button’.

Compare the fused image with the original image