Method and device for film-mode detection

A method for film-mode detection comprising:

• concurrently providing pixel samples from three successive fields;
• comparing corresponding pixels P1 and P4 from corresponding lines of said first and third fields respectively, to vertically aligned pixel pairs, P2 and P3, from successive lines of said second field, and between which said pixels P1 and P4 are vertically disposed;
• allocating a first value to the results of respective comparisons if the amplitude of pixel P1 is intermediate the amplitudes of pixels P2 and P3, and the amplitude of pixel P4 is not intermediate the amplitudes of pixels P2 and P3, and allocating a second value if the amplitude of pixel P4 is intermediate the amplitudes of pixels P2 and P3, and the amplitude of pixel P1 is not intermediate the amplitudes of pixels P2 and P3,
• collating the results of comparisons over respective field intervals, and assigning said first or second values to respective fields depending upon whether comparisons for respective fields produced predominantly said first or said second value;
• and
• comparing the sequence of first and second values assigned to successive field, for a predetermined pattern.

A method for film-mode detection comprising:

• concurrently providing pixel samples from three successive fields, wherein first and fourth pixel samples from a first and third of said successive fields respectively, are vertically disposed between second and third pixels from a second of said three successive fields;
• comparing said first and fourth pixel values with said second and third pixel values to determine whether said four pixel values represent contiguous image contours;
• assigning a positive or negative value to the results of respective comparisons depending upon whether contiguous image contours are determined to occur;
• summing the results of comparisons over respective field intervals, and assigning first or second values to respective fields depending upon whether the sum of results of comparisons for respective fields are positive or negative;
• and
• comparing the sequence of first and second values assigned to successive fields, for a predetermined pattern.

An apparatus for film-mode detection comprising:

• an input terminal for applying a video signal;
• delay means, coupled to said input terminal, for concurrently providing pixel values from adjacent fields of video signal;
• a means, coupled to said delay means, for comparing amplitude values of respective pixels from corresponding image areas of said adjacent fields to determine whether amplitude values of respective pixels in successive adjacent fields are in a first or a second monotonically increasing or monotonically decreasing relationship;
• and
• means, coupled to said comparing means, for determining if the comparison results over at least a portion of respective field intervals indicate that respective pixel amplitude values of said respective field intervals are predominantly in said first or second monotonically increasing or decreasing relationship, and assigning a first or second value respectively to said respective field intervals according to the predominance determined;
• and
• means, coupled to said means for determining, for establishing film mode detection if a resulting sequence of said first and second values assigned to a predetermined number of said respective field intervals corresponds to a predetermined pattern.