Controlling the focus of a camera using focus statistics

A method of controlling camera focus, the method comprising:

• forming a characteristic for each block of a plurality of blocks of a frame, each block of the plurality of blocks comprising at least one pixel;
• calculating a parameter for each block of the plurality of blocks by combining the characteristic of that block with the characteristics of other blocks having a predefined spatial relationship to that block;
• receiving an indication of a selected region of the frame;
• and
• forming a measure of focus for the selected region of the frame by combining the parameters from a set of blocks in the selected region.

A non-transitory computer readable storage medium having stored thereon computer readable instructions that, when executed at a computer system, cause the computer system to:

• form a characteristic for each block of a plurality of blocks of a frame, each block of the plurality of blocks comprising at least one pixel of a camera;
• calculate a parameter for each block of the plurality of blocks by combining the characteristic of that block with the characteristics of other blocks having a predefined spatial relationship to that block;
• receive an indication of a selected region of the frame;
• and
• form a measure of focus of said camera for the selected region of the frame by combining the parameters from a set of blocks in the selected region.