Building OpenCV using STM32 Discovery Boards

I use Keil MDK 5.20. I have 2 boards.

STM32F4DISCOVERY - 32-bit Cortex®-M4F STM32F407VGT6 MCU, 1MB Flash, 192KB RAM
(Max freq. 168 MHz)
32F746GDISCOVERY - 32-bit Cortex®-M7 STM32F746NGH6 with FPU, 1MB Flash, 340KB RAM
(Max freq. 216 MHz)

With the 32F746GDISCOVERY, a connector P1 with the DCMI(Digital Camera Interface)
signals is available to connect a camera module such as STM32F4DIS-CAM (ST order code).

Since both boards have example codes for getting data from the camera module,

I tried to plan to use OpenCV for face detection with those boards.

The latest versions of OpenCV is 2.4.13 (2016-05-19) and 3.1 (2015-12-21).

I want to use those libraries to detect faces with the DISCO boards.

Questions: How can I compile and build the OpenCV libraries using Keil MDK 5.20?

-Best Regards, David