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Streaks on stacked image.

 
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courtany



Joined: 10 Jun 2011
Posts: 16
Location: Nottingham England

PostPosted: Wed Jul 20, 2011 12:43 am    Post subject: Streaks on stacked image. Reply with quote

I have just done a 32 frame stack of a plants seed case but there are some streaks on the final image that I can't understand. It was taken against a plain background so I can't see where the marks have come from. The frames were taken with a Stack shot and stacked in Zerene using pmax. I know the lightings rubbish but I can sort that out, it's the streaks I'm bothered about as it's the second stack it's happened on. Any help would be much appriciated. Picture hopefully below (knowing past record with sending pictures. Very Happy
Cheers Keith.

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rjlittlefield
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Joined: 01 Aug 2006
Posts: 19405
Location: Richland, Washington State, USA

PostPosted: Wed Jul 20, 2011 1:12 am    Post subject: Reply with quote

The streaks are probably sensor dust. In individual images, they will appear as slightly dark round spots, not too obvious. But when scale is adjusted from frame to frame so as to make the subject line up, sensor spots get expanded into these radial streaks that are very obvious. The best solution is to use a clean sensor. Another approach is to retouch the background (where the streaks normally occur) from a single input frame. This will convert the streaks back to ordinary spots, and will also reduce the background noise that PMax brought out because it couldn't distinguish between sensor noise and real detail. Switching to DMap would also help, but many people find that tool more difficult to use when they are just starting with stacking.

In rare cases, streaks like these come from actual spots on the background. But usually those are not so long or so well defined, so I think more likely sensor spots.

--Rik
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courtany



Joined: 10 Jun 2011
Posts: 16
Location: Nottingham England

PostPosted: Wed Jul 20, 2011 1:48 am    Post subject: Reply with quote

Thanks for the quick reply Rik I'll give it a clean up.
Cheers Keith
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