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I am using a canon ixus 300 HS camera and configured it to shoot RAW (DNG) by using CHDK (version: 1.0.0-1825; latest build for ixus 300 HS). At first sight, all seems ok and the DNG's are generated nicely, but when looking closely (ie. zooming in), there are a lot of stuck/dead pixels on the image.

Although the CHDK documentation stated that for DNG dead/stuck pixels are always resolved (apparantly this is mandatory for DNG standard) by using some kind of interpolation algorithm, it does not work no matter what I set as 'Bad pixel removal' option (Average or RAWConv.) I still see the dead/stuck pixels. I have generated the badpixel.bin file for this to work without any errors.

My question now is how to solve this either in CHDK or even better in post-processing where I have more control (in the latter case, preferably in Darktable, not LR)?

Detail with stuck pixels: https://www.dropbox.com/s/j35pcba3hz37ovs/DetailWithStuckPixels.png Original DNG: https://www.dropbox.com/s/mufnsrxcqzfbnwj/CRW_6640.DNG (ca. 16MB)

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  • \$\begingroup\$ I've tried the hot pixels module in DT, but it does not help (some are found, but most are not) \$\endgroup\$
    – Sven
    Commented Jun 29, 2012 at 11:29
  • \$\begingroup\$ you mean you've tried this? \$\endgroup\$
    – philops
    Commented Jul 2, 2012 at 14:25
  • \$\begingroup\$ Yes, but as stated in my question (and answer below), it does not work with the latest build of CHDK for the ixus 300 hs that can be found on the site. It works now because I used a newly compiled version posted by somebody in the CHDK forums. \$\endgroup\$
    – Sven
    Commented Jul 3, 2012 at 14:42

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Apparently there is a more recent build of CHDK for this type of camera that can be found on the forums: http://chdk.setepontos.com/index.php?topic=7864.0

Downloaded & installed it and works fine now. The newly generated DNGs are free of dead/stuck pixels now...

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