All Things Color for Film and Digital Cinema
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iRiS – Photochemical Color Timing Reference Image

Here is a color reference image I generated for quickly visualising Color Density Readings. You should ask your lab to write down their density readings of the LAD / 445 CV grey patch at the head of each Roll on each Box/Can of print film you receive. With this information you can immediately determine if the print is a “little magenta” or a “little dark” and pre warn clients before a screening that the neg is OK but this particular print out of that particular days processing bath is a biased in that direction.  

Click the LINK HERE for a downloadable version.


iRiS - Lab timing reference

iRiS - Photochemical Lab Timing Reference Image



The printer light settings on the rotary dials are arbitary 25-25-25 settings. More than likely each lab changes these settings each day after calibrating themselves to the processing bath using a sensitometric wedge. I have personally found it is better to talk to your Lab consultant in terms of printer point changes      IE +1 red -2 Green +1 Blue      rather than actual printer lights, 26 23 26, as this can cause confusion. 

For example if your print had a LAD density reading of 1.03 1.06 1.03 you could deduct that the print was a little Red and a bit lighter. IF though the print LAD was “on AIM” ie 1.09 1.06 1.03 but you still thought the print was a little red you could ask in subsequent prints for a trim of -1 Cyan (the complimentary opposite of RED) which would result in a print that was less red and a fraction darker. The numbering seems a little counter intuitive but referencing the numerics on the RGB rotary wheels you can see that subtracting one point on the red ‘wheel’ you would be pushing it up (making 25 become 24) which in turn is letting less red light through. This in turn makes the Green and Blue ‘lights’ more visually dominant, hence Cyan. 


 Coming very soon is my visualization Application for MacOSX that is pretty much the above user interface but provides realtime color feedback to the image of your selection with adjusted printer lights using your preferred input 3DLUT. Very useful for dealing with your film LAB of Choice when making and timing Answer Prints.

If you would like to know any more about this application please feel free to email me.





Adrian Hauser

3 Responses to “iRiS – Photochemical Color Timing Reference Image”

  1. rayray says:

    Hello Adrian.

    Wow, it will be very useful application.
    When it possible download for testing ?


  2. admin says:

    HI andrey,
    How did the test go? I’m glad to hear it worked on the MacBookPro.
    It will not work on the standard MacBook as that version processor does not support some implementations of OpenGL I am using.

    What version QT, OpenGL and OS are you running on your MacBookPro?

    Updates to Come,
    Full screen UI with live quicktime/firewire camera output to external screen.
    Export function to QT and SOP controls.


    • Andrey says:

      Hi Adrian,

      MBP 2.4 Unibody MacOS 10.5.6 QT 7.6.0 don’t know about OpenGL.
      I send mail to You about some bugs.

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