histogram in the graphic card

I need to obtain a color histogram of a synthetic image in the frame buffer. I want compute the histogram in the graphic card, without transferring the frame buffer to the CPU. With glHistogram, I can’t do it without a previous glDrawPixels or a glCopyPixels, which makes impossible run my application in real time.

Is there a solution for this problem for the cards NVIDIA (GeForce 3 or GeForce FX5900) or ATI Radeon 9800 PRO?

Thank you

As I know, on PC only Wildcat3/4 support ARB_imaging(including histogram) in hardware(and it is in real-time) - all other - just in software.