Patent EP-1081959-A1 (EP)
Inventor: PAU DANILO
IPC: H04N7/26
Filed: 1999-09-03
Abstract: A method of recognizing a progressive or an interlaced content of video pictures
during their processing in a coder, comprises the following operations on at least
on one of the components (luminance or chrominance) of the video signal:
   a) defining a macroblock belonging to a frame of the preceding picture having
dimensions R*S pixels, a half of it (R/2)*S being placed on the Top field  Tp  and
the other half on the Bottom field  Bp ;   b) for the chosen component of the video signal, calculating a first pair of
coefficients (COEFF_1, COEFF_2) equivalent to
   the sum, extended to all the columns and to all the even row of said macroblock,
of the absolute values of the differences among the values assumed by said
component of the video signal in the pixels of the same column and of
consecutive rows belonging to the Top semi-frame and Bottom semi-frame,
respectively, and   the sum, extended to all the columns and to each fourth row of said macroblock,
of the absolute values of the differences among the values assumed by said
component of the video signal in the pixels of the same column and of
consecutive rows of the same parity belonging to the Top semi-frame and Bottom
semi-frame respectively;     c) verifying whether the first one of the coefficients of said pair is greater than
or equal to a prefixed first real positive number of times (a) of the second
coefficient, incrementing a first counter (CONT_1) at each positive verification;   d) incrementing a second counter (NUM_MACROBLOCK) at each macroblock so
tested;    e) calculating for each row of each Top semi-frame a second pair of
coefficients (COEFF_3, COEFF_4) equivalent to
   for each row the sum, extended to all the columns of each semi-frame of the
absolute values of the differences among the values assumed by said component
of the video signal in pixels of the Bottom semi-frame of the preceding picture
and of the Bottom semi-frame of the current picture, belonging to the row
following the considered row and to the same column, and   the sum, extended to all the columns of each semi-frame of the absolute values of
the differences among the values assumed by said component of the video signal
in pixels of the same column and, respectively, of said row of the Top semi-frame
of the preceding picture and the row following the considered row, belonging to
the Bottom semi-frame of the current picture, respectively;     f) verifying whether the second coefficient of said second pair is grater than or
equal to a second prefixed real positive number of times (β) the first coefficient of
said second pair, incrementing a third counter (CONT_2) at each positive
verification;   g) incrementing a fourth counter (NUM_RIGHE) at each row so tested; 
verifying whether the content of the first counter (CONT_1) is greater than or equal
to a third prefixed real positive number of times (γ) the content of second counter
(NUM_MACROBLOCK) and whether, at the same time, the content of the third
counter (CONT 2) is greater than or equal to a fourth prefixed real positive number
of times (δ) the content of the fourth counter (NUM_RIGHE): if so, considerating
the frame composed of said Top and Bottom semi-frame an interlaced one, if not
a progressive one.