Noise detector, noise removal circuit and border emphasis circuit

摘要

PURPOSE: To correctly detect a noise component by calculating a noise coeffi cient based on a quantity and a direction of a luminance change. CONSTITUTION: An A/D converter 10 converts an analog luminance signal ya in into digital luminance data ya in , which are given to a filter memory 11. The filter memory 11 stores plural 2-dimension unitary differentiation filters FHn with different directions and each filter output is given to a gradient detector 12. The gradient detector 12 calculates an absolute value of the output of each filter and gives its maximum value abs (v) and a filter number (n) of the 2-dimension unitary differentiation filter FHn producing the abs (v) to a noise coefficient calculation device 13. The noise coefficient calculation device 13 calculates a noise coefficient (c) representing possibility of the input signal affected by noise based on the abs (v) and (n).