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Old Dec 22, 2002, 9:47 PM   #1
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Default What are these white pixels on my photos?

For the first time ever (I've owned digital cameras for the past 6 years) I'm seeing white pixels on my photos. They appear anywhere in the image and are usually surrounded by a green border. Has anybody else seen this? Could the camera (a c-50 z) be defective? By the way, this problem is most noticeable at SHQ resolution (presumably 5 MP?)
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Old Dec 22, 2002, 11:46 PM   #2
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Sounds like hot or dead pixels. Does the C50 have pixel mapping? Check your manual. Pixel mapping will correct the problem. If not you will have to have it repaired.
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Old Dec 23, 2002, 1:18 AM   #3
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Thank you for the tip! It does have pixel mapping and I've already run it. The camera is brand new, though. I've just had it for one day and have shot about 100 pictures. Is this some sort of "calibration"?
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Old Dec 23, 2002, 1:49 AM   #4
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It is common for digital cameras to develop dead pixels. The pixel mapping feature interpolates the dead pixels and artificially fills them in. It is usually all that is needed, however it is a bit early in the life of your digicam to develop hot pixels. If the problem persists you should contact Olympus and return the camera for a warranty CCD replacement.
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Old Dec 23, 2002, 2:01 AM   #5
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I was also wondering if the terrible image quality I've been getting could be related to this. I've tried all the resolutions in the different modes, and at the highest resolutions (actually at all resolutions except the lowest) the pictures turn out very "blocky", I don't know what the right word is to describe it, but it's basically like many of the pixels on the picture are brighter than others, so what is supposed to be a high-res 5 mp picture looks worse than a picture from a 2 mp camera. By the way, I did the pixel mapping and tried taking a couple of pictures, and even though I couldn't see any white pixels (didn't look hard enough), image quality is still the same.
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Old Dec 23, 2002, 2:34 AM   #6
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I would return the camera for an exchange or refund.
Let's also get the terminology correct, hot pixels are not the same as dead pixels.
Dead pixels are just that - they have stopped working altogether and will appear as spots on the images in the same place on every shot at all exposures. They can be mapped out with the pixel mapping function (which is precisely what it is designed for).
Hot pixels on the other hand manifest themselves only with long exposure times, typically greater than about half a second, and increase in number as the exposure gets longer. These are individual sensors (pixels) in the CCD array (CCD=Charge Coupled Device) that start to leak charge during longer exposures. The effect is bright spots sprinkled across the image. Some pixels are worse than others which is why the effect is worse with longer exposures. This cannot be fixed with pixel mapping. All cameras are subject to this effect but some include firmware for removing the effect before you see the final image.
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Old Dec 23, 2002, 6:08 AM   #7
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Let's add to that:

Dead pixels are always off and appear black.

Stuck pixels are always on and appear the colour they are (red, green, or blue).
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Old Dec 23, 2002, 7:26 AM   #8
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Nora
I would return the camera. The C50Z should not have all the problems you have describe on your many post.
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Old Dec 23, 2002, 11:26 AM   #9
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Thank you all for your comments. They're very informative and you're all very knowledgeable and helpful. After seeing the definitions of the different types of pixel problems, I think "hot pixels" best describes my case. Do you know of any sites where I could see some samples just to make sure? I tried looking for some but only found examples of dead and stuck pixels. And yes, I will definitely return this camera. Unfortunately I live in Mexico (three hours away from the border) and will have to wait until after Christmas to go back and return it.
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Old Jan 2, 2003, 7:45 PM   #10
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A simple way to test for hot pixels is to take a picture in a dim or dark room, with no flash, and the lens cap on. This will yield a black frame with only hot pixels, if any, visible.
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