Dilly Of A Pickle: The Phantom Dead Pixel at DVinfo.net

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Old January 4th, 2007, 09:45 PM   #1
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Dilly Of A Pickle: The Phantom Dead Pixel

Okay... I need some help.

I might have a dead pixel... I might not.

On some night-time footage I recently shot (with a redrock M2) I have a bizzarre white spot that appears in a constant spot on my footage. It seems to be about 1 or two pixels tall and one or two pixels wide. It doesnt' seem to respond to colour or light, so I do not think it is a piece of dust or anything.

Now, it is strange. The "dead" pixel was there for much of my shooting, but after I stopped recording, and started again, it mysteriously vanished, and has not reared it's ugly white head since... I am confused though, because it is was almost certainly something electronic, not a physical object on the lens.

I will post a clip shortly.


Essentially... is it possible for a pixel to die and come back to life? Is it possible for short-circuts to exist which cause all the RGB pixels to fire at once creating white, but vanish at times?

I am confused...

Matt
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Old January 4th, 2007, 10:16 PM   #2
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what camera are you using?
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Old January 4th, 2007, 10:49 PM   #3
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James, he's posting in the XH G1 / A1 camcorder forum. It's safe to assume that he was using an A1.
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Old January 4th, 2007, 11:05 PM   #4
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Thanks Chris,

www.notomatofilms.com/Pixel.jpg


I know it's small, but it's there and unmoving. Will post a video shortly.

Image is upside down due to the M2... squeezed due to the 1.33 anamorphic ratio... nosiy due to gain. Ugly due to my face :)

It has since disappeared, but it is there for the full 30 min we were filming, seems unaffected by light and dark (so unlikely it;s fluff or a lens defect).

I am just concenred cause, even though my cam is working now, I cant have it crap out right before my big shooting coming up. Also, it cant be seen on the onboard LCD, so impossible to know if it's back.

Note: We shot with a variety of gain settings and presets, and it was present through all...
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Old January 4th, 2007, 11:18 PM   #5
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From past experience with an old Sony Betacam I used to use, a pixel can intermittently die and come back to life. A friend of mine told me you can sometimes mask dead pixels by performing a black balance on the camera. I tried it and it did work quite a few times, but after a certain time frame the pixel was lost for good.

I realize I am not referring to an A1, but just wanted to let you know that it is possible for the pixel to come and go.
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Old January 5th, 2007, 07:52 AM   #6
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Hmmm, so they aren't Dead pixels, they are Zombie pixels...

This is no good.
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Old January 5th, 2007, 12:59 PM   #7
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Actually, it's not dead or zombie. Technically it's hot pixel.

If it's always visible at 0dB gain, then you have right to consider it a defect, subject to free service.

Hot pixels at higher gain are formally allowed to be visible. The problem could also be temperature related. Working in hot room, under kilowatts of light power can affect the CCDs or CMOS sensors thermally, but once the temperature returns to normal, hot pixel(s) should not be visible.

It is also possible video processor in A1/G1 cams is smart to detect hot pixels and mask them after you restart your camcorder.
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Old January 5th, 2007, 03:45 PM   #8
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Well, my camera has gone into Canon service, so we'll see what happens. Regardless, there is definatly something afoot...
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