Hi, I already recommended this board to some one on this group and I think that the board meets your requirement. It is RTG-005 from Hunt Engineering. Detailed manual is available from their website; and luckily the source code (which they offer in accompanying CD) is in VHDL.
Try their Demo in which monochrome video from camera link is grabbed, various image processing filters being managed in FPGA are available in user control (in a gui) and results are displayed on computer screen via usb interface from the board.
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