[RPi] Flat-Field and Colour Correction for the Raspberry Pi Camera Module

哇賽，校正好文。 

* https://openhardware.metajnl.com/articles/10.5334/joh.20/

* https://www.spiedigitallibrary.org/journals/journal-of-electronic-imaging/volume-26/issue-01/013014/Laying-the-foundation-to-use-Raspberry-Pi-3-V2-camera/10.1117/1.JEI.26.1.013014.full?SSO=1