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Subject: Re: ACR Calibration

Les Helgeson wrote:

> But I notice that the summary average Delta H and S values for "colors
only" are virtually identical for all three options … <<


Thanks a lot for sharing your test results! I think that the last sentence as quoted above sums it up very well. Because HSB-hue and –saturation (which together represent the ratios of R:G:B ) are providing a quite handy definition for ‘color’; whereas I suggest to ignore the brightness differences and the absolute RGB numbers. The Calibrate tab has no Y or brightness sliders anyway, and tone curves are meant to change the tone from accurate to pleasing. … As expected, and as far as I can see:

ACR calibration allows you to *redistribute* all color errors involved – which under certain provisions can lead to more pleasing results with regard to the specific colors you’re most interested in (see e.g. the relocation of the saturation error from green to red). Also, ACR calibration allows you to *re-coordinate* the coloring with your preferred tonal settings – means to absorb saturation changes from leaving the preset tone curve.

ACR calibration *cannot reduce* the total error across all colors, when your camera is essentially the same as the ‘sample’ which was profiled by Adobe. Batch deviations in fact seem to be a myth. And the total error should be hardwired with the design of Bayer filters.

This leads back to the ‘probing’ question already raised above. It would be kind if Adobe would give us a hint – concerning the cameras which behaved best when the generic profiles were built (lowest rest-error / total error across all colors). I’m just asking because I’m intending to buy a new camera this year….




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