Can I view Lab values with a color sampler?

Submitted by grateful on Sat, 03/17/2018 - 15:02
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Can I view Lab values (Lab Color Readout values?) with a color sampler in FRV? An important part of my culling process is checking the Lab value of the white patch on the x-rite ColorChecker targets in my photos. It is not enough for me to know that the white patches are not overexposed. For example: a photo of a ColorChecker Digital SG target with a white patch L value of 97 is better than one with a L value of 99, but FRV seems to give me no way of distinguishing between the two. Am I missing something?

LibRaw

Sat, 03/17/2018 - 17:46

Dear Sir:

L* is not in a raw file, it is a matter of interpretation in your raw converter, each will do (slightly) differently. When shooting a target, it is better to use RawDigger for evaluation. Make sure you have 0.3 to 0.5 EV between clipping and the white patch. To know the clipping point, you can shoot a specular highlight on a curved shiny surface, like a ball. Set the exposure in such a way that the highlight is small (check the green channel in RawDigger to see the size of the highlight), and the raw values on the highlight in the green channel will provide the clipping point.

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