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I am working on a scientific application where I would like to evaluate luminance in an image, however I am unsure if what I receive from my setup is luminance (Y) or luma (Y'). I use a camera with a TOSH IK CU51 (PAL) control unit which is connected via S-Video to a Canopus ADVC-300 analog to digital converter. The digitized data are streamed to a computer and presented in YUV2 format.

Now the problem: I read into luminance and luma and realized that I do not know if gamma compression is applied somewhere on the way between the camera and the computer, so that really I am getting Y'UV2 instead of YUV2, is there e.g. a definition for a PAL signal to be gamma compressed and for an S-Video signal not to be corrected?

Edit: As there are no answers yet, I think I should be more specific: Is there any flexibility in the PAL or S-Video standard or in how a device is generally expected to work where I would have to take gamma correction into account? A little more background: luminance is proportional to energy per spatial area. If gamma correction were applied then I'd get a somewhat distorted value. If I knew gamma, I could adjust for this.

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  • $\begingroup$ Thanks, @ObscureRobot! I flagged the question and asked for moving it to dsp.SE $\endgroup$ – Sebastian Feb 16 '13 at 11:05
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You should photograph a known calibration target with your system, (like this one or the one that I put in the thumbnail).

enter image description here

This will allow you discovering the OECF of your system. You can either calculate it by yourself, given the technical data sheet or use third-party software like Imatest, ImageAnalyzer or others.

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  • $\begingroup$ @Sebastian, consider accepting the answer if it helped you. Thanks $\endgroup$ – Andrey Rubshtein Feb 19 '13 at 17:48
  • $\begingroup$ I hope to get an answer that involves definitions and specifications. Your answer is helping a lot, but it isabout testing an actual setup. Sorry, if I was not really clear about it. $\endgroup$ – Sebastian Langer Feb 21 '13 at 9:20
  • $\begingroup$ @Sebastian, ok, you are right. $\endgroup$ – Andrey Rubshtein Feb 21 '13 at 11:15

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