Bug in all CHDK DNG 1.3 files prior to Feb 18 2017 (trunk r4756) ?

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Caught this thread in the dpreview.com forum last week : Software to process CHDK raw files from Canon compacts?

Apparently there has been a bug in CHDK DNG 1.3 bad pixed correction opcodes for some time.  It has now been fixed in the autobuild stable and development releases but I'm kind of surprised nothing was reported here as well   :-[

If I understand the problem correctly,  the Bayer pattern used to create bad pixel correction opcodes for DNG 1.3 was not correct. (A Bayer pattern defines which pixels are have red, green, or blue filters in front of them).   This would cause post-processing software to incorrectly "fix" bad pixels when using CHDK generated DNG 1.3 images.

philmoz send one user a command line script to repair a few existing images. 
Ported :   A1200    SD940   G10    Powershot N    G16

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Offline philmoz

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Re: Bug in all CHDK DNG 1.3 files prior to Feb 18 2017 (trunk r4756) ?
« Reply #1 on: 25 / February / 2017, 18:39:02 »
I suspect Adobe has changed the algorithm they used to fix the bad pixels.
Previously, even though the bayer pattern was wrong, PS & LR still seemed to do an OK job, so the problem was not readily noticeable.


Attached is the source for the program I created to fix existing files.


Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)

 

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