Artefacts in output file

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James Cooke
Posts: 3
Joined: 15.06.2020 12:36

Artefacts in output file

Post by James Cooke » 19.06.2020 16:50

I am seeing lines of bright dots on some output images after stacking. This example is from 120 RAW files stacked using Method C in Helicon Focus 7.6.3. Images were shot using Helicon Remote with a Canon 5D4 and Sigma 105mm f2.8 macro lens.
2020-06-15 16-15-42 (C,Smoothing4).jpg
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A close up of these are shown below:
Annotation 2020-06-15 112718.png
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I also see these on the intermediate image as Helicon Focus is building the final image - see the screenshot below.
Annotation 2020-06-15 112718 2.png
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There is no obvious source for these artefacts on the source images. The lines on the intermediate image converge on the centre of the screen which makes me think they may be due to dust spots, hot pixels or similar.

Can you tell me what could be causing this effect?

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Joined: 29.04.2019 22:38

Re: Artefacts in output file

Post by Catherine » 21.06.2020 14:54

These artifacts seem to be coming from hot pixels on the source images that turn into this kind of pixel streaks on the output during processing.

In order to check for the source of these streaks, please render the stack, zoom into the area with the artifact on the output, with high magnification, so that separate pixels can be seen, hover the cursor over the streak/dot and press F9. This will display the source image this area has been taken from and will show if you have these dots on the source images.

Helicon Focus has a dust map feature designed to deal with dust spots and hot pixels: ... ml#HF_DUST

In order to create a map of hot pixels, please use dark of black background - for instance, take a picture with the lens cap on.

Please note that dust map should have the same dimensions as all the other images in the stack.

James Cooke
Posts: 3
Joined: 15.06.2020 12:36

Re: Artefacts in output file

Post by James Cooke » 21.06.2020 17:13


I've done a detailed check for hot pixels and found they correspond with the pixel streaks on the image stack. Thanks for confirming.

I have done a pixel remapping procedure on my camera and the hot pixels no longer appear.

I will use the dust map feature in future to deal with any dust spots.

Thanks for the help.

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