Banding Reduction

In some cases, images may suffer from a banding defect. This is usually caused by the sensor, or appears in short exposures due to electronic noise; calibration by darks, bias and flats do not improve the images.

The banding reduction window dialog has some parameters to optimize the processing:

Amount defines the strength of the correction. The higher the value the stronger the correction, but a value of 1 should be good in most cases as it applies the same correction as ideally computed.
Protect from Highlights will ignore bright pixels when the option is checked, this can be useful for images with large bright objects.
Sigma Factor will adjust the highlight protection. Higher value will ignore only pixels that are brighter.
Vertical banding removes vertical banding instead of the default horizontal banding. This should rarely be needed, but some cameras also have this problem.

Applying the following filter to the original image, with parameter values as shown in the illustration, gives a nice result free of banding.

This filter can also be applied to a sequence. Adjust the filter for the loaded image (with a sequence already loaded), then check the Apply to sequence button and define the output prefix of the new sequence (unband_ by default).

Siril command line

fixbanding amount sigma [-vertical]

Tries to remove the horizontal or vertical banding in the loaded image.
amount defines the amount of correction, between 0 and 4.
sigma defines the highlight protection level of the algorithm, higher sigma gives higher protection, between 0 and 5. Values of 1 and 1 are often good enough.
-vertical option enables to perform vertical banding removal, horizontal is the default

Siril command line

seqfixbanding sequencename amount sigma [-prefix=] [-vertical]

Same command as FIXBANDING but for the sequence sequencename.

The output sequence name starts with the prefix "unband_" unless otherwise specified with -prefix= option

Links: fixbanding