Walking noise and how to remove it

Walking Noise comes from fixed pattern noise on the camera sensor, which is made worse by imperfect polar alignment (drift) or lack of dithering. It appears as faint, coloured "streaks" like "rain" across the background of the final, stacked image. The camera's fixed noise moves slightly with each shot. When software stacks the images, these noisy pixels are averaged into linear artefacts.

The DWARF mini smart-scope performs automatic dithering during astrophotography captures. For exposure times under 60 seconds, the DWARF dithers after every 6 captured frames (the 7th frame is used for dithering). For exposure times of 60 seconds or longer, the DWARF dithers after every 10 captured frames (the 11th frame is used for dithering). Frames captured during the dithering movement are intentionally discarded and are not saved to the device.

This imaging session captured only 8 x 90s frames of M3 (12 minutes total exposure).  This means that it didn't dither during the session, which was stopped due to clouds. Any walking noise is likely to show in the stacked image.

The 16 bit png stacked image was used for this test.

Click on an image to get a closer view

The Cosmic Clarity Walking Noise De-noiser in SetiAstroSuitePro was used. It is also available as a SetiAstro script in PixInsight.

Screenshot of SetiAstroSuitePro running the Cosmic Clarity Walking Noise De-noiser

Looking at this image closely by clicking on it will show the walking noise 'rain'.

Screenshot of SetiAstroSuitePro after the de-noiser has been run

Looking at this image closely by clicking on it will show that the walking noise has gone.

Blink animation of the before de-noising and after dew-noising the image

The image should be examined closely to observe the walking noise removal.

I have another article on this subject HERE.

Steve Wainwright