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I had asked a question previously here which though not duplicate but is related to this. Asking this one as I feel it is different. My question is basically related to colour balancing/colour correction in raw image,post processing tools.

  1. I give as input to Adobe-PS, a raw captured, DNG file for post processing. This DNG file has a) A Raw bayer 16-bit per sample data. b) A preview RGB image of smaller size. c) Lot of metadata.
  2. Then I just save this image opened in Adobe-PS as a BMP file. i.e. no processing/filtering is done in Adobe-PS.

  3. Then I modify the Colour matrices metadata information present in the DNG files and repeat steps above. The outputs are differemt.

Questions:

  1. Exactly Which metadata information from the DNG file or from its own database, does Adobe-PS use to perform colour balancing/colour correction. The DNG file has below tags which I thought are related to Colour balancing- a) AS shot whtie XY b) 2-Color matrices1 c) Calibration Illuminant 1/2

  2. I know for sure that Adobe definitely uses Color matrix information as I explained above.

But my question is along with these matrices, Adobe sure seems to use something else/or uses these matrices after some scaling or in a different way, because when I use these matrices in my own image processing tool, they produce a different output/colours. So in what all ways and how does adobe differ in colour balancing/correction is done.

P.S. I did not see any XMP metadata files which could have some colour profile info in Adobe installation folders or in some other Adobe folders on my PC. But I did notice a lot of files in a folder called Presets(image shown below) in Adobe installation. What are these files and what info they contain?

enter image description here

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I think this is getting downvotes because people feel that programming an image processing pipeline is off topic. But it's also kind of long and hard to follow. (And I think the screenshot actually makes things worse in this case.) –  mattdm May 19 '11 at 20:43
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@goldenmean those folders are for presets of their namesake tools, e.g. Gradients/ includes different gradient settings for use in i.a. gradient-tool and gradient overlay -effect; and Black and White/ includes preset settings for Black & White tool found under Image → Adjustments. I think they are not relevant for this question. –  koiyu May 19 '11 at 21:57
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@goldenmean I don't understand the question nor the problem: You take DNG & output BMP#1; then you modify DNG-metadata & output BMP#2; the BMPs differ—isn't that the desired effect? Which metadata did you change? How does your image processor's output differ from PS? Or are you asking for a list of all other possible tags that affect the Raw→composite processing? –  koiyu May 20 '11 at 19:11
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@goldenmean: I'll echo @mattdm here; if you want better results you need to ask your question better (note, I did NOT say 'ask a better question!'). As it stands your question is filled with rambling tangential asides which (based on the feedback you're seeing) is making the question hard to find, and also hard to answer. I'd definitely recommend taking a look at Jon Skeet's excellent article "Writing the Perfect Question" for ways you can reformulate yours in order to "help us, help you!": msmvps.com/blogs/jon_skeet/archive/2010/08/29/… –  Jay Lance Photography May 25 '11 at 18:08
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@Chris: you say mean spirited, I say: hey look, this isn't getting good answers. Let's figure out why not. While it's nice when people format their answers, that's not all it takes to ask a question well. (Those other questions should be closed too, of course — it's a false dichotomy to say that because those are bad this one must be voted up.) –  mattdm May 31 '11 at 21:54

1 Answer 1

From your question I gather the following process:

  • Open a DNG file in Photoshop, and immediately save it to BMP.
  • Open the DNG XML metadata file, switch up some values, save.
  • Open the same DNG file in Photoshop, and immediately save it to BMP.

This apparently produces different results. Your question is answered. If you modify the DNG XML metadata file, that must be what is used to render the image in Photoshop.

Furthermore, if you are concerned with specifically changing a certain value(eg white balance), and wondering if a change in the DNG XML metadata file will alter the output, you can simply run through the process and see if it changes it or not(I'm assuming here that it will).

Any data that is not present in the DNG file will not simply be changed by Photoshop. The only thing Photoshop will do is change values to output to the format you select. If you are taking a photo from one colorspace to another, it will modify what is needed to match that output colorspace for example.

To further enhance and clarify the question and its answers I would remove the screenshot of the filter presets and either link to the metadata file and its associated changes or show a screenshot of what you changed in it.

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