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New project: camera color profile calculation

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Offline Sess

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Re: New project: camera color profile calculation
« Reply #210 on: 18 / June / 2008, 22:04:22 »
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Let me see if I understand the purpose of this project. By comparing the raw and jpg, you can figure out how each camera interprets the colors in the raws and converts them to jpg. With this information, you can make DNG4PS-2 better interpret the colors in the raw files when it creates a dng. Is that right?

The big downside for me using raw files is that when I open the subsequent dng files in Lightroom or ACR, they auto pick a white balance that is way off from what the camera chose. Would calibration help programs like Lightroom and ACR pick a better white balance when they open these dng files?
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Offline oversky

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Re: New project: camera color profile calculation
« Reply #211 on: 18 / June / 2008, 23:10:47 »
Sess, lightroom can choose WB as shoot, tone curve as linear.
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Offline Sess

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Re: New project: camera color profile calculation
« Reply #212 on: 19 / June / 2008, 01:51:55 »
Quote from: oversky on 18 / June / 2008, 23:10:47
Sess, lightroom can choose WB as shoot, tone curve as linear.

The CHDK raw files have no white balance info and neither do jpgs used when making dng files. So when you set the white balance in Lightroom to "As shot" it is really just doing "Auto" and making its best guess based on the photo. The problem is the best guess in Lightroom for the raws from my A650 is always way off from what the camera chose for the jpgs.

From reading this thread it sounds like DNG4PS-2 needs to be properly calibrated for each camera, otherwise the colors in the dng files it makes will be skewed. In other words, Lighroom is choosing the correct white balance for the photo it is given, it's just that the photo it is given has skewed colors to begin with.
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DawMatt

Re: New project: camera color profile calculation
« Reply #213 on: 19 / June / 2008, 10:51:48 »
Quote from: lks on 07 / June / 2008, 16:28:22
The new matrix is quite good in daylight conditions.  Significantly better than any of the past matrices, including the 720is.

In lower temperature light (2800 to 4000 degrees) the colors and white balance of the new matrix get out of whack.  I will try again to make a calibration under Tungsten light -- it hasn't worked well the first few times.
Assuming you are using DngSetMatrix to apply the matrix, I think its limitations are part of the issue here.

When setting M1 and M2 it doesn't allow us to set the illuminant for each matrix, nor delete the current color matrix value.  Not an issue if we have valid values for the two default illuminants, but when we set both M1 and M2 with the same color matrix values we are explicitly telling the graphics viewer/editor to use our color matrix for that illuminant even though we know it is wrong.  No wonder things get "out of whack".

Options:
  • When initially generating the DNG make sure you use a camera that only fills in one matrix, and that the matrix uses the desired illuminant
  • Use some other program to massage the color matrix/illuminant values so only the valid matrix ends up in the final DNG
  • Let me know when people have a matrix we are comfortable with and I can add it into the program, though Denis will still need to release the final build

Thanks,
Matt
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DawMatt

Re: New project: camera color profile calculation
« Reply #214 on: 22 / June / 2008, 05:51:44 »
lukg,

Which of matrix do you consider the best, and are you confident that it is better than the one currently being used by the program?  If so I might build a test release for you to try out, esp. to see how the full program copes when converting photos under tungsten lighting (etc).

Thanks,
Matt
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Offline lukg

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Re: New project: camera color profile calculation
« Reply #215 on: 22 / June / 2008, 05:59:10 »
Hi Dawmatt, I'm using this matrix:

Camera -> XYZ matrix:
1,943902 0,442380 0,815924
0,215457 2,022005 -0,092312
0,021941 -0,780416 5,443674
XYZ -> Camera matrix:
0,531769 -0,148074 -0,082215
-0,057135 0,513726 0,017275
-0,010334 0,074246 0,186507

It's surely better than the one included in dng4ps2, simply because there's no S5 matrix in DNG4PS2 yet (only S5is label but the matrix from a different camera afaik) :D
« Last Edit: 22 / June / 2008, 06:04:01 by lukg »
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Offline ArtDen

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Re: New project: camera color profile calculation
« Reply #216 on: 23 / June / 2008, 12:16:19 »
lukg, 0.2.2beta-26 contains test matrix for S5. Please test it and tell which matrix is better (mine or yours)
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Offline lukg

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Re: New project: camera color profile calculation
« Reply #217 on: 23 / June / 2008, 12:27:32 »
Ok, thank you! I'm going to test it.
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Offline lukg

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Re: New project: camera color profile calculation
« Reply #218 on: 23 / June / 2008, 12:55:59 »
I did a quick test using my sample images, and the matrix in dng4ps2 is reddish for almost all the pictures.

Here are 2 examples.

Right = my matrix
Center = dng4ps2 matrix
Left = jpg

http://img410.imageshack.us/img410/1789/catturamv9.jpg (look at the wood)

http://img410.imageshack.us/img410/3664/cattura2mw6.jpg (here all is reddish)
« Last Edit: 23 / June / 2008, 13:04:53 by lukg »
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Offline ArtDen

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Re: New project: camera color profile calculation
« Reply #219 on: 23 / June / 2008, 13:15:55 »
Have I include your matrix into dng4ps2?
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