Patent ID: 6590617
Filing Date: 2003-07-08
Classification: H04N

Abstract:
An edge emphasis device comprising:a first absolute value computation circuit arranged to compute an absolute value of a difference between a target signal and a lead signal obtained before the target signal by a predetermined time; a second absolute value computation circuit arranged to compute an absolute value of a difference between the target signal and a later signal obtained after the target signal by a predetermined time; a minimum value selection circuit arranged to select a smaller one of the absolute value computed by said first absolute value computation circuit and the absolute value computed by said second absolute value computation circuit; a second-derivative signal generation unit arranged to generate a second-derivative signal based on the target signal, the lead signal and the later signal; a second-derivative signal suppressing unit arranged to suppress the second-derivative signal generated by said second-derivative signal generation unit; a multiplying unit arranged to multiply the second-derivative signal suppressed by said second-derivative signal suppressing unit and the absolute value selected by said minimum value selection circuit; and an adding unit arranged to add the signal outputted by said multiplying unit to the target signal, wherein said second-derivative signal suppressing unit comprises: a minimum value selection circuit arranged to compute an absolute value of the second-derivative signal and to select a smaller one of the computed absolute value and a predetermined value; and a sign determination circuit arranged to determine the sign of the second-derivative signal generated by said second-derivative signal generation unit.