Method and electronic circuit for optical motion sensing

An electronic circuit (10) for an optical motion sensing device (1), the electronic circuit comprising (10):

• a processor (18) and a storage (16);
• an image acquisition unit (11) configured to store a reference image (12) and a current image (13) to be compared with the reference image (12);
• a correlation engine (14) connected to the image acquisition unit (11) and configured to determine a correlation coefficient between the reference image (12) and the current image (13) for each one of numerous displacements between the reference image (12) and the current image (13);
• and
• a search engine (15) connected to the correlation engine (14) and operable to compare the correlation coefficient of each displacement between the reference image (12) and the current image (13) with a predefined threshold correlation coefficient,
• wherein the search engine (15) is operable in one of a preliminary search mode and an accurate search mode, wherein when in the accurate search mode, the search engine (15) is configured to store the correlation coefficient obtained from the correlation engine in the storage (16).