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12-12-2014, 10:47 AM   #1
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Single bad pixel on my photos

I have a K20D and although its a great workhorse, several months ago I noticed a white hot spot on my pics. Always in the same location. In some pics it stands out very obvious, but of course in other pics it blends right in. I find I have to clone it out of all pics that I edit. Is this a proposition that means whole sensor replacement or is it repairable? Unfortunately I don't have a picture with me to post, I'm not at home.

12-12-2014, 11:04 AM   #2
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Does pixel mapping fix the problem? I have this feature in the menu on my K30.
12-12-2014, 11:10 AM   #3
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Yes, I think the K20D has pixel mapping -- check your menus. That is exactly the problem it is designed to fix. All sensors get bad pixels over time (especially for long exposures). Many RAW converters will detect them and interpolate them out on import (Lightroom does this), but the pixel mapping feature on the camera does the same permanently. (Makes a note of the bad pixels and interpolates them.)
12-13-2014, 12:58 AM   #4
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Yes the K20 has pixel mapping. At the Set up menu (little wrench!)

Page 235 owners manual.

12-13-2014, 09:35 AM   #5
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Pixel Mapping

I will try that. I've never heard of it and I'll be tickled to death if it works!

I am at home now and able to attach a few samples of the issue (normal pic and 2 zoomed). Thank you!!!
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12-13-2014, 09:51 AM   #6
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Well, it shows a lot bigger than a bad pixel, but running the pixel mapping set up will not hurt.

Every single sensor has some bad pixels. This are mapped out at the final stage of quality control when camera is made. In fact, there is no single sensor ever that has no bad pixels. All of them from every manofacturer has them. You wouldn't believe how many bad pixels can be found (pre-mapping) on a 14 Mb sensor. Around 200 to 300 bad ones!

The pixel mapping runs a diagnostic and detects every pixel not producing a signal. It maps it out and tell the camera's computer to "always ignore this pixel and replace its missing information with an average information from the surrounding pixels" Don't worry, it takes clusters of 30 to 50 bad pixels in a single group to "tell" a defect in a picture, and yet, such bad cluster will have to follow exactly where a miniscule detail of the picture is to be able to tell a difference.

Go ahead, run the utility at set up menu level in the K20. In order to avoid false readings from stray light coming through lens, use your lens cap on or remove lens and use body cap for the procedure. Sometimes, it may take running the utility more than once to map out all the bad pixels, especially if they are found in a small cluster like a 4 x 6 bad pixel spot.
12-13-2014, 10:22 AM   #7
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Yeah, that looks like more than one pixel and usually they show up as a color like green or red rather than white... but a sensor stain would be dark. Try it anyway...
12-13-2014, 10:29 AM   #8
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Does it exist in the camera when you zoom the view or only when loaded to Lightroom (or other software ) ? It could that that your default loading preset has some radial filter or some spot removal option ON at import time and so all photos would get it. It seems to be unusually large for a hot or dead pixel.

(Lovely model btw

01-02-2015, 10:12 AM   #9
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Hi Everyone,

So sorry it took so long to get back to you. I hope you all had a great Christmas and New Year's holiday!

I just wanted to update you all about the suggestion that "pixel mapping" might help the situation with my K20 camera. And I'm happy to report that IT DID!!

I usually only use the camera for special occasions and situations, hence the delay. But, this morning I opened my email and the Pentax Forum group had sent me a "Happy New Year" email and it jogged my memory just enough to review this thread. I grabbed the camera and thought to myself that this is surely going to be more difficult process since I've never heard of anyone doing this before. The process is like formatting a SD card, easy-peasy! It was over in less than 10 seconds.

I did 4 test shots with a dark background and with the lens cap on the lens and it worked flawlessly. I am so tickled about this win and that my camera is like new again!!!

Thank you, thank you, thank you!!!

Happy New Year's to you all!!!!
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