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Old October 5th, 2009, 01:11 AM
Tony Whitaker Tony Whitaker is offline
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Default 5D MkII image anomaly

I have found an anomaly occurring when I shoot raw+jpeg. This manifests itself as a small array of red pixels near the middle of the image. It is 5 pixels H by 9 pixels W with brightest red running horizontal thru the middle then fading in both directions, similar to a jpeg compression array. I have narrowed down that it appears to be a problem with the jpeg processing rather than dead pixels on the sensor as the raw images do not display any error even when viewed at 3200% or pixel level. It is independent of lens or whether flash is used or not. It does not occur when shooting jpegs only. It is in exactly the same position on every image. Anybody else experienced this problem or any ideas on what may be causing it? Thanks
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Old October 5th, 2009, 02:00 AM
Bart_van_der_Wolf Bart_van_der_Wolf is offline
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Originally Posted by Tony Whitaker View Post
I have found an anomaly occurring when I shoot raw+jpeg. This manifests itself as a small array of red pixels near the middle of the image. It is 5 pixels H by 9 pixels W with brightest red running horizontal thru the middle then fading in both directions, similar to a jpeg compression array. I have narrowed down that it appears to be a problem with the jpeg processing rather than dead pixels on the sensor as the raw images do not display any error even when viewed at 3200% or pixel level. It is independent of lens or whether flash is used or not. It does not occur when shooting jpegs only. It is in exactly the same position on every image. Anybody else experienced this problem or any ideas on what may be causing it? Thanks
Hi Tony,

When you say it's not in the Raw data, be aware that some Raw converters eliminate Dead/Hot pixels without asking. The only way to really be sure is by looking at the Raw data itself. Also, when the same phenomenon occurs at the same position in different images, it would be suspect.

Cheers,
Bart
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Old October 5th, 2009, 09:40 AM
Mike Shimwell Mike Shimwell is offline
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Originally Posted by Bart_van_der_Wolf View Post
Hi Tony,

When you say it's not in the Raw data, be aware that some Raw converters eliminate Dead/Hot pixels without asking. The only way to really be sure is by looking at the Raw data itself. Also, when the same phenomenon occurs at the same position in different images, it would be suspect.

Cheers,
Bart
I don't think DXo maps out hot pixels automatically, so that would be an alternative way to see if that's the problem. One or two hot pixels culd cause such a problem if they aren't mapped out.

Mike
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Old October 5th, 2009, 12:10 PM
Tony Whitaker Tony Whitaker is offline
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Thanks, Mike & Bart ... we (my son is a professional photographer also running a 5D mkII, and he's been looking into it with me) had considered this but because this problem does not occur when shooting only jpegs we had dismissed the possibility of a dead pixel. One thing we have not looked at yet is whether the problem occurs at all jpeg conversion settings as so far I have only ever operated with the large files. We'll try a series of test shots later today and see if we can work out just which combinations of RAW/jpeg are affected. Tony.
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Old November 29th, 2010, 01:31 AM
Kenneth Wiley Kenneth Wiley is offline
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Just curious if you have the latest firmware installed?
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