Fix image pixel access methods to be safer.
Fix image pixel access methods to be safer.

iabdalkader/openmv,iabdalkader/openmv,iabdalkader/openmv,openmv/openmv,iabdalkader/openmv,kwagyeman/openmv,kwagyeman/openmv,kwagyeman/openmv,kwagyeman/openmv,openmv/openmv,openmv/openmv,openmv/openmv