I'm having trouble finding a color wheel/color picker that meets my needs. Anyone know of anything?

I need something like the Mac Color picker, that is, a circular representation with hue (angle) and saturation (radius) depicted in a circular color map.

Here's a description of the Mac Color Picker: http://www.robinwood.com/Catalog/Tec...colorPickerApp

I also need it to output the color value of whatever pixel I select.

Finally--and here's the part that trips me up--I need it to be large. As big as my laptop screen if possible. Eight to ten inches a measured on the screen at minimum.

I'm not worried about HSL or HSV or the details of the output numbers. I can be an app, a feature in another program, or a bit of Python or other programming code that I can run.

Alternatively, if you know of some way to do this mathematically that would work, too. I can give a position within a circle. I would need back the hue and saturation of that position.

Seems simple but I can't find what I need after hours of googling. As usual, I may be missing something obvious.