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Converting CHDK RAW files to something DXO PhotoLab 2 will read

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Online philmoz

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Re: Converting CHDK RAW files to something DXO PhotoLab 2 will read
« Reply #20 on: 27 / May / 2020, 01:22:43 »
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This maxes out the green/purple tint slider in RT, so something is clearly not right, but I don't know what it is.


Using dng_validate:


Image 1105 EXIF has - ExposureProgram: Program Normal
Image 1858 EXIF has - ExposureProgram: Unidentified


In addition the raw pixel values in the masked area at the bottom vary from around 126 to 133 in image 1105.
In image 1858 they are all exactly 128.


My guess is the image was taken on a scene mode, or some other mode setting, and the raw hook saved the data after the firmware had already done some processing on the raw data for the JPEG conversion. I've seen similar results when the raw capture hook is set too late in the capture sequence.

If that's the case then colour matrices may have already been applied to the raw image data, so the matrices in the DNG file are causing double processing. Maybe try setting them to a unity matrix in the DNG file? (doesn't help).

Phil.
« Last Edit: 27 / May / 2020, 02:25:47 by philmoz »
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Re: Converting CHDK RAW files to something DXO PhotoLab 2 will read
« Reply #21 on: 27 / May / 2020, 13:56:09 »
Yes, there's something odd with this and the other ones. I don't usually use scene modes, but I'll have a look at them to see if the ExposureProgram is consistently not normal.

There's one which happened just as the battery was running out, but the others are fairly random (and fortunately not common!)

Re: Converting CHDK RAW files to something DXO PhotoLab 2 will read
« Reply #22 on: 27 / May / 2020, 16:48:08 »
Ah, dng_validate is Windows / Mac source from Adobe and building it on Linux involves quite a few additional steps. I'll see if I can do it before going away for a couple of weeks.

Out of 2,634 DNG files, it looks like it affects 28, or a fraction over 1% of them here. Interestingly, if I look at those 28 DNGs in DxO Photolab, the ones that were clearly taken in portrait orientation are shown in landscape, so the orientation bit of the file wasn't being set correctly either.

Re: Converting CHDK RAW files to something DXO PhotoLab 2 will read
« Reply #23 on: 27 / May / 2020, 17:02:03 »
This one is weird. It looks like a bad CFA at first glance, but on closer inspection I pretty sure it's not: There are small areas of fairly solid green in the foliage. White balancing on the lighter tiles in Raw Therapee gives me the attached, which looks like it could be roughly correct, except for the sky which is massively over-exposed. Of course, I don't know what the colors on the mosaic are supposed to be, but they look Italian :haha

This maxes out the green/purple tint slider in RT, so something is clearly not right, but I don't know what it is.

The CFA related DNG values (active area, CFA pattern, default crop) are the same as the other image (IMG_1105.DNG) we looked at earlier. The camera WB values are different, but not wildly so, and swapping in the IMG_1105 white balance values doesn't have any significant effect.

I found the memory card - the JPEG turned out ok and you've done a good job in recreating it!

The sky was indeed massively overexposed (metering on the centre of the image, which was in shade on a bright Rome summer day). The blur was, I think due to having my elbow jogged by the kid in the other picture (DxO PL'd).

https://imgur.com/a/MkJZvRy


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Offline reyalp

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Re: Converting CHDK RAW files to something DXO PhotoLab 2 will read
« Reply #24 on: 27 / May / 2020, 17:17:50 »
I found the memory card - the JPEG turned out ok and you've done a good job in recreating it!
If you upload the original jpeg (something like dropbox rather than imgur if it's too big for the forum), we might be able to figure out what mode or setting caused the issue.

The issue appears to be in the actual data, so that probably won't help you recover the images, but could help others avoid having the same issue in the future.
Don't forget what the H stands for.


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Offline reyalp

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Re: Converting CHDK RAW files to something DXO PhotoLab 2 will read
« Reply #26 on: 28 / May / 2020, 14:56:11 »
Thanks

https://www.dropbox.com/s/nrwitz1h73w0roc/IMG_1858.JPG
Thanks.
exiftool says
Quote
Canon Exposure Mode:Easy
Easy Mode:High Dynamic Range
That probably explains the weird raw. CHDK raw isn't expected to work in HDR modes.
Don't forget what the H stands for.

 

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