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Old Jan 19, 2006, 1:44 PM   #1
Lin Evans's Avatar
Join Date: Jun 2002
Posts: 1,141

I had a cluster of about five dead (hot) pixels on my R1 and Sony's technical service was less than helpful, at least for my needs.
All sensors have dead pixels and firmware has mapping algorithms which substitute adjacent good pixel values for those missing from these regions. Sometimes - actually more often than not - a cluster or so of hot pixels slip by and are not mapped. Some companies such as Olympus provide the user with mapping software and user upgradeable firmware correction to keep the sensor's output pristine in appearance. As a sensor ages, more "hot" pixels will begin to appear. It's quite easy to see hot pixels when taking night exposures and the number increases with exposure time and subsequent "heat". Many manufacturers have what is called "dark frame" subtraction where your exposure is compared with a hot pixel mapped dark frame and any hot pixels are "removed" from the exposure. This effectively doubles the time necessary to wait for your image. For example if you take a 3 minute exposure at a given aperture then a corresponding "dark frame" is taken immediately afterward by the firmware. This value is then used to remove the offending noise and hot pixels but the trade-off is that you must wait double the exposure time or "six" minutes to get your results.

Sony told me that they have no user software to fix hot pixel issues and that I should send my R1 to them for "evaluation" to see if it is or is not within tolerance. That's unacceptable to me for fixing a cluster of about five visible pixels which show up as a rather small red dot. Of course it's simple enough to clone out these offending dead pixels using PhotoShop, but that's also annoying to have to do for every image where they are conspicuous. So I set out on a quest to find a software solution.

I found an excellent software program written by Max Lyons. Max also writes an excellent GUI front end for PanoTools to facilitate making stitched panoramas, but I wasn't aware of his very nice pixel zapping software. I downloaded the trial shareware version (it only works for 640x480 or smaller images) and tried it with superb results. I then bought the software ($15 U.S.D.) and within 15 minutes of downloading the trial had a full working version which does a beautiful job. The software is VERY flexible and you get two flavors. It only works on jpg files but saves them in a lossless fashion so is still very useful. It can also output BMP format, but the jpg's are virtually indistinguishable from the originals except the offending hot pixels are gone...... If you download it, be sure to also download the help file for the GuI version. You get two versions for the price of one. There is a script enabled command line version and the GUI version. Each can handle single or folder containing multiple images to process.
Here's a link for anyone interested:


Best regards,

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