Color Sampler Tool in ACR

When you open a RAW file with ACR from PS CS2, you can see the Color Sampler Tool (fourth icon from the left). What's exactly the function of this icon?

It's the same as the Color Sampler in Photoshop itself - you can choose one or more points, and display the RGB values. One possible example for using it is if you have a particular point you wish to get near a mid tone - you could set a Color Sampler on it, then keep an eye on the values to see when they near 127.

I do confess that I've never used it when post-processing, though.

David

In photoshop proper I used to use a the color sampler tool, the one that would let me specify up to four different colour points (although I'd just use three). I'd do a shot with a grey scale built into it - say a portrait with the model holding the greyscale. Then I'd create a colour adjustment layer and point the color sampler at three points on the card, dark grey, middle grey and light grey. I'd adjust the colours (using the info pallette) trying to get all three colour components to be equal. Something like the light grey (and I may well be getting this backwards) to be all 233 in red, blue and green. Then I'd adjust the middle grey sao that all of its component colours were equal, and then I'd do the same for the dark grey.

Almost always I'd find that if I corrected two of the three the third correction would slightly affect one of the first, 233, 233, 235; that kind of thing, but this is close enough. What all of this gave me was an imperical, don't-care-what-my-monitor-looks-like, neutral colour correction that any lab could use to make a great print.

I'd then take this color adjustment layer and drag it onto the "real" portraits (or whatever). This was particularly useful since there's rarely a neutral black or white in a shot without a grey scale present.

With the Camera RAW CS2 that same tool is there but I've never been able to make it work in the same way, since the Colour sampler looks like it can have one recorded point. I want to make ALL of my colour, density and the like in Camera RAW so the adjustment layer trick has gone. I hope that CS3 introduces the ability to have at least three recorded points and a way to see the effect of all three points at once like the info pallete will.

Right now I'll occasionally use the color sampler to pick out a white to see what that'll do, but it's not nearly as useful as that old adjustment layer trick.