Image display apparatus and contour detecting circuit provided therein

An image display apparatus comprising:

• a second differentiating circuit to compute a second-differentiated value based on an input video signal;
• a determining circuit to detect timing with which a polarity of the second-differentiated value obtained by said second differentiating circuit is inverted;
• and
• a computing circuit to perform a steep-contour generating process on an input video signal corresponding to the timing detected by said determining circuit such that a contour of said input video signal is steep,
• wherein said computing circuit has a generating mechanism to generate, from said input video signal with said predetermined timing and first-differentiated values based on the input video signals adjacent to said input video signal with said predetermined timing, interpolation data between adjacent input video signals.

An image display apparatus, comprising:

• a first differentiating circuit to compute a first-differentiated value based on an input video signal;
• a second differentiating circuit to compute a second-differentiated value based on said input video signal;
• a detection-computing circuit to obtain a degree of a change in said input video signal with predetermined timing from a first-differentiated value based on an input video signal with said predetermined timing and a first-differentiated value based on at least one of input video signals adjacent to said input video signal with said predetermined timing;
• a determining circuit to detect timing with which a polarity of the second-differentiated value in said second differentiating circuit is inverted, and to determine, by referring to a computation result by said detection-computing circuit, which corresponds to said predetermined timing, a contour of said input video signal to be processed by a steep-contour generating process;
• and
• a computing circuit to perform, based on a determination result by said determining circuit, said steep-contour generating process on said input video signal.

A contour detecting circuit, comprising:

• a first differentiating circuit to compute a first-differentiated value based on an input video signal;
• a second differentiating circuit to compute a second-differentiated value based on said input video signal;
• a detection-computing circuit to obtain a degree of a change in said input video signal with predetermined timing from a first-differentiated value based on said input video signal with said predetermined timing and a first-differentiated value based on at least one of input video signals adjacent to said input video signal with said predetermined timing;
• and
• a determining circuit to detect timing with which a polarity of the second-differentiated value by said second differentiating circuit is inverted, and to determine, by referring to a computation result by said detection-computing circuit, which corresponds to said predetermined timing, a contour of said input video signal.