Difference between ACR Calibration and Colorchecker Passport

Started Apr 26, 2013 | Discussions thread
malch Forum Pro • Posts: 14,265
Re: Difference between ACR Calibration and Colorchecker Passport

naththo wrote:

So having white background is no good for that target because it would create uneven illumination. And that chart is possibly not parellel to the plane of sensor. And not having done any multi exposure. So thats the problem. If the illumination is uneven it would make it looks like some square are darker than the others and that would totally interfere with calibration.

So I can understand clearly what you explain what causes of problem to the accuracy of calibration since target should be lit even against grey background and parallel to the plane of sensor while taking multi exposure to pick the correct exposure to use for calibration.

The grey background isn't essential but it sure helps to confirm the evenness of the illumination. If the all four corners around the test target have the same RGB values, you know the lighting is pretty darn even.

But the main point is... you want to take considerable care when making the test shots you'll use to create the camera profile. Without that, you'll just have one more experiment that demonstrates the principle of Garbage In, Garbage Out.

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