Digital Light & Color

I'm experimenting with Camera Profile builder. The (probably misconceived) idea is to build a single profile for use in the field (at variety of illuminations). To build this single profile, I was hoping to use Macbeth at some standard illumination, fixed WB and standard processing so that it corrects for camera colour quirks in a semi-standard fashion, but still allows for colour changes due to different lighting and WB (no changes in processing).

Is that a workable idea?

If it is, what illumination should I choose to shoot this single target? My guess is that the profile tries to bring colours in the test image illuminated by some light in the field, to what the reference file predict for those colours to be if the target was illuminated by D65? So I figured that if I match the test target illumination to be close to 6500K CCT, that would make the Camera Profile that corrects mostly for camera/processing colour inaccuracies and not that much for colour changes due to illumination?

Would a 'mid-day, somewhat overcast sky (some blue left), with no direct sun' light be a good idea to achieve something close to D65?

Or is it all unnecessary, and it's enough, for the generic camera profile, to shoot target at any light and set the WB so that the gray patches of the target come out neutral before using the Profile Builder?

The best use for a custom profile is for studio work where you have consistent lighting. What the profile will do is to correct for the color temperature of the lighting and any nonlinearities of the camera and sensor to produce an image of the scene as if illuminated by a specific type of lighting.

You should be able to use a profile generated in mid-day sunlight to make a more of less generic profile, but this will make images taken under incandescent light appear very yellow and images illuminated by skylight blue, which is the whole reason cameras have white balance settings. Sometimes you might want to keep the color cast such as sunset-illuminated landscapes and sometimes you might not such as photographing objects on a copy stand for sale on eBay, so there is no one profile that is going to work for all conditions.