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How to open with technical flat calibration in 7.0

Apr 25, 2012 3:07 PM

Tags: #7.0 #linear #flat_calibration

In earlier versions, Camera Raw gave an option to set "Blacks" = "Brightness" = Contrast" = "0", and set a straight tone curve.  With color space set to Adobe RGB, this opens with EXACTLY a calibrated power of 2.2.  This gives a very flat looking image with no "S" curve that no one would use for beauty, but when used for SCIENTIFIC applications, I can raise the 16-bit image to the 2.2th power in Photoshop and have EXACTLY a linear correspondence between photon count and pixel count.  This lets me add photons, divide images to normalize, make exact pixel by pixel measurements, and a lot of things us scientists like to do unrelated to making pictures beautiful.

 

Camera Raw 7.0 changed the sliders, and after hours of scientific experimenting I can not find a combination that opens images that are technically exactly flat (gamma 2.2 of course) without deviations to the straight curve.

 

I do weddings occasionally, science mostly, and Photoshop is my go-to tool for both.  Thanks in advance for your help advancing the cause of science.

 
Replies
  • Currently Being Moderated
    Apr 25, 2012 4:13 PM   in reply to q38

    q38 wrote:

     

    Camera Raw 7.0 changed the sliders, and after hours of scientific experimenting I can not find a combination that opens images that are technically exactly flat (gamma 2.2 of course) without deviations to the straight curve.

     

    You can't...but what you CAN do is create a custom DNG Profile in DNG Profile Editor that has a flat, linear curve and use that profile as the basis of a no curve starting point. Also note that the new PV 2012 does some auto highlight recovery and the image adjustments are based on image adpative range and end point settings.

     
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  • Noel Carboni
    23,523 posts
    Dec 23, 2006
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    Apr 25, 2012 6:38 PM   in reply to q38

    q38 wrote:

     

    Camera Raw 7.0 changed the sliders, and after hours of scientific experimenting I can not find a combination that opens images that are technically exactly flat (gamma 2.2 of course) without deviations to the straight curve.

     

    Is this true if you choose the PV2010 development process?  I had thought that was supposed to still be identical to what it was before.

     

    PV.jpg

     

    Nothing says you HAVE to use PV2012 to develop your scientific images.  You can set the development process into the Camera Raw defaults or create a Preset.

     

    -Noel

     
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  • Currently Being Moderated
    Apr 25, 2012 8:25 PM   in reply to q38

    There's a lengthy discussion about this in the LIghtroom forum:

     

    http://forums.adobe.com/message/4289492#4289492

     
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  • Noel Carboni
    23,523 posts
    Dec 23, 2006
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    Apr 26, 2012 4:44 AM   in reply to q38

    I suspect scientific analysis is exactly in the opposite direction from which Camera Raw is heading, so you may be right about it being an impossible dream.

     

    Something to consider might be to look into the various software packages made for astroimaging.  I think you might find that, since astroimagers must do some oddball things (such as stack multiple exposures) the software there may be capable of giving you low level extractions of raw files.  I do know that some astroimagers (myself included) use dSLR gear.  It's been a while since I did it, and the old program I used to use - Images Plus - might be able to see into raw files.  Another one that comes to mind is Maxim DL.

     

    -Noel

     
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