How can you assess tonal value of colours?

[ChrisS]

I need to know the best way to assess the tonal values of ceramic glazes. To do this, the glazes are being photographed and the photographs converted to greyscale in PS. In-camera processing is being minimised by shooting RAW. I know the monitor (and later printer) needs calibration if the tonal values are to be consistent.

Is there anything else I should be doing? I need to exclude 'taste' and subjective judgement from the process in so far as I can.

Also, am I overlooking any specialised equipment that can measure tonal values?

Thanks for any advice.

Chris

[Jonathan Wienke]

Get an Eye-One spectrophotometer and the free Eye-One Share app that goes with it. It can be used to make highly accurate color measurements of any opaque material, and the results can be displayed as LAB values. The L channel value should be of particular interest to you.

[ChrisS]

Get an Eye-One spectrophotometer and the free Eye-One Share app that goes with it. It can be used to make highly accurate color measurements of any opaque material, and the results can be displayed as LAB values. The L channel value should be of particular interest to you.
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Thanks Jonathan.

Chris