Reducing the effects of Hot Pixels in RawTherapee

I have recently looked at the mitigation of the effects of Hot Pixels that for one reason or another can end up in an astronomical deep sky image using software such as GREYC's Magic for Image Computing.

I am here using RawTherapee to reduce the effects of Hot pixels. RawTherapee is cross-platform software: It is available for Linux, macOS, and Windows. It is free and Open Source: RawTherapee is released under the GPLv3 license. It works perticularly well with a number of RAW formats, but is also very powerful with a large number of other image formats such as TIFF or PNG.

Click on an image to get a closer view

A section of an image of the Andromeda Galaxy showing red green and blue Hot pixels

An image file containing hot pixels was loaded into RawTherapee and the Details tab was selected. The following is the set of controls that were used together with their settings. (it must be remembered to experiment with settings for each individual image.

Details tab

    Impulse noise reduction

        Threshold 55

    Noise Reduction

        RGB

            Aggressive

            Gamma 3

    Median Filter

        Weighted

        Median type 7*7

        Median iterations 3

Animation showing before and after applying the above controls to the image

Although it is better to avoid hot pixels if possible. RawTherapee is able to substantially mitigate their effects.

Steve Wainwright