Describing chromaticity differences - New tutorial article

[Doug_Kerr]

In many areas of photographic practice, we are concerned with the difference between two chromaticity values, especially in connection with “white balance color correction” matters. An example would be the departure of the recorded image of a “white” object from the reference white chromaticity of the color space in use, or the departure form “neutrality” of the reflective chromaticity of a “neutral target” (gray card).

I have just posted to my technical information site, The Pumpkin, a new tutorial article, "A Metric for Chromaticity Difference", available here:

A Metric for Chromaticity Difference

In it, I suggest the use of a metric, called "du'v', to describe the degree of such chromaticity differences.

The metric is defined and a rationale given for its use. An appendix defines the way this metric can be calculated from the sRGB coordinates R, G, and B of the two colors whose chromaticity we wish to compare. An available spreadsheet is also described that can be used to perform this determination.

[Doug_Kerr]

I have just determined that in the spreadsheet described by the referenced tutorial article, there is an error in one of the formulas (the one in column "I").

The error was a sign error, and (fortunately) did not have any effect on the calculated value of du'v', but did produce a sign error in v' and dv'.

The file has been replaced by a corrected one.

My apologies for any inconvenience this error may have caused.

Best regards,

Doug

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