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01/03/2003 09:38:46 AM · #1 |
I'm having trouble with my camera on long exposures. It's putting dots of colour on the image which are very annoying. I assume this is a problem with the CCD. Example at:
//www.sucs.org/~dez/gallery/Tests/aaa
(This is just a photo with the lens cap on and the shutter open for 8 seconds. Click on the image to see it full size)
I tried to reduce the impact of this on my submission to the New Year challenge by removing the blue from the image (the only dots that appeared in my crop were bright blue). Nevertheless, someone commented on them, as I expected they would.
Has anyone else come across this and what have they done about it?
I expect to rectify this problem properly, I would have to take the camera to be repaired. Is there anything I can do to remove or at least reduce the impact of these marks on my images that is legal under DPChallenge rules? |
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01/03/2003 10:53:36 AM · #2 |
This is normal for a Nikon 950 I think. It was a thing not properly dealt with at the time the camera was made. Nowadays most cameras have anti-noise software that corrects the "stuck / hot" pixels and some of the newer ccd's are less sensitive to it.
Check dpreview's review of the 950, on
this page there's an item about this under "Stuck-on" pixels on long exposure images, with an example.
It is not a camera failure, when they put another ccd in the same will happen at other places.
It can become worse when the ccd ages I was told, but you've got to verify that.
I believe that Neatimage is an allowed tool to get rid of this. It is used to correct noise. I have never used it, so I don't know what it can do with stuck pixels.
There is another method with Photoshop or other programs that work with layers. There is a way to substract the hotpixels of you lenscap image from the normal images with the stuck pixels in them (they are supposed to be always on the same place). I don't know it this is allowed under the site's rules.
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01/03/2003 10:58:17 AM · #3 |
Here is a link to a page of the review of the Nikon 990, that has the same 'problem'. It also describes how to correct the image with the photohop method I mentioned above.
It is under the "Low Light" section.
Ask the site council if this is allowed.
Message edited by author 2003-01-03 11:01:36.
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01/03/2003 11:02:10 AM · #4 |
I had a few hot pixels on my Canon, for the little bit of noise that I did get I would just adjest the lighting down in PS 1 to 3 points and it took care of the noise.
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01/03/2003 11:39:15 AM · #5 |
I'm having a play with Neat Image now. So far, I'm very impressed.
I sent a photo of the night sky I took in July through it. It hasn't done anything about the stuck-on pixels, but I'll play with layers in PSP to deal with that.
Before and After |
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01/03/2003 11:52:12 AM · #6 |
This page has a couple of free tools for hotpixel removal (as well as several other useful programs) including one that doesn't require a 'black frame'. I had a great deal of success with it when I had the same problem with my first digicam.
Again, you will need to check with the site council to see if it is legal for challenge entries.
Message edited by author 2003-01-03 11:53:00.
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01/03/2003 12:20:53 PM · #7 |
I've now tried BlackFrame NR and HotPixels (from the link above)
Results in my Test gallery. Neither program seems to have done a great job of removing the blue and orange hot pixels and the results using the layer method were unpleasant (as they left gaping black holes in the image). |
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01/04/2003 09:57:07 AM · #8 |
Since HotPixels would be editting individual pixels of an image, this would probably be classed as spot-editting and thus would not be allowed in DPC submissions (Note: this is my personal guess, not the final ruling).
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