TFP410: On the connection between TFP410 and DS90UB913A-Q1

I would like to send RAW12 images from a personal computer using TFP410 and DS90UB913A-Q1.
How can I convert TFP410 output (24 bits) to match DS90UB913A-Q1 input (12 bits) using FPGA?
The following image:
(raw12)-> HDMI -> TFP410 -> FPGA -> DS90UB913A-Q1

Thanks!