White balance (?) issues with S3 IS raw - RAW Shooting and Processing - CHDK Forum
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White balance (?) issues with S3 IS raw

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Offline Special

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White balance (?) issues with S3 IS raw
« on: 05 / July / 2008, 22:53:04 »
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I've noticed that, when handling RAW files created by CHDK and processed by DNG4PS-2, the white balance on the output DNGs seems to be wildly incorrect. I haven't tried particularly hard, but i've been unable to find any easy set of presets in lightroom that will rebalance the images. As an example:

A photo in JPEG, as output by the camera, unedited (though resized):


The same photo in raw and processed to DNG, also unedited: (click to see larger)


The raw image has a very strong blue tint, and white is more of a light blue than a white at all. I tried calibration with the instructions on the CHDK wiki, but the results seemed to change nothing (after being applied with dngsetmatrix) - although i'm not entirely confident of that. If there is a better way to test these, please let me know.

Is there an easy solution to this? All of my photos go through lightroom, so if it can be corrected with lightroom's adjustments in a uniform manner (the same for any image), that'd be perfectly fine.
« Last Edit: 05 / July / 2008, 23:32:31 by Special »
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Offline ArtDen

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Re: White balance (?) issues with S3 IS raw
« Reply #1 on: 06 / July / 2008, 00:26:08 »
dng4ps2 guarantees idenitical of color only if photo was taken with daylight illumination. With other illuminations you have to correct white balance in you RAW developing program.
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Offline b3nj1

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Re: White balance (?) issues with S3 IS raw
« Reply #2 on: 18 / July / 2008, 19:50:14 »
FYI, after converting my SD600 shots to DNG using DNG4PS-2, I found that irfanview (versions 4.1 and 4.2) picks up the as-shot white balance automatically when viewing and converting the DNG. The converted DNG appeared the same as the JPG. Picasa2 did not (not a big deal to me since Picasa has other issues like clobbering maker notes in the exif/meta data).

- Benjamin
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Offline vit40

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Re: White balance (?) issues with S3 IS raw
« Reply #3 on: 18 / July / 2008, 20:12:57 »
It's not possible, because there is no as shoot white balance info in dng, produced from CHDK raw files
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Offline ArtDen

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Re: White balance (?) issues with S3 IS raw
« Reply #4 on: 19 / July / 2008, 00:08:01 »
vit40, Last beta of dng4ps2 contains color profile for SD600
« Last Edit: 19 / July / 2008, 00:12:03 by ArtDen »
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Offline dzsemx

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Re: White balance (?) issues with S3 IS raw
« Reply #5 on: 19 / July / 2008, 00:41:59 »
you're lazy...chdk raw des not contain white balance information
for ex. rawtherapee works directly with chdk raws and there is no accurate auto white balance so i have to set it manually...just a few seconds...
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Offline b3nj1

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Re: White balance (?) issues with S3 IS raw
« Reply #6 on: 19 / July / 2008, 12:01:48 »
I may be a bit lazy and certainly a little crazy.

Canon DPP and ZoomBrowser do not show Color Temp info for shots from my 40D or my SD600 (chdk and normal shots). Exiftool picks it out for my 40D, but not the SD600.

So, I'm not exactly sure how it's stored, but it does seem to work. Here's a screenshot of my ultra creative test shot. On the left is the JPG in irfanview, in the middle is the DNG4PS2 CRW->DNG shot in irfanview, on the right is the same DNG loaded in Picasa2.




- Benjamin
« Last Edit: 19 / July / 2008, 12:05:05 by b3nj1 »
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Offline fudgey

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Re: White balance (?) issues with S3 IS raw
« Reply #7 on: 19 / July / 2008, 14:22:40 »
CRW files written by CHDK do not have any white balance information in them. That's why Picasa can only guess. DNG4PS2 is a lot better at it, because it has a better guess for S3IS white balance in it, based on images taken on such a camera.
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Offline b3nj1

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Re: White balance (?) issues with S3 IS raw
« Reply #8 on: 21 / July / 2008, 12:04:37 »
Quote from: fudgey on 19 / July / 2008, 14:22:40
CRW files written by CHDK do not have any white balance information in them. That's why Picasa can only guess.

Note I'm referring to the handling of DNG files, not CRW files. On the same DNG file that DNG4PS2 converted, Picasa does not pick up the white-balance while ifranview does.

Anyway, I love irfanview. and it's already part of my flow. So if I shoot RAW on my SD600, I'm pleased I can continue using it. YMMV.

- Benjamin
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