| 摘要 |
PURPOSE:To obtain the contour lines with high accuracy by supplying a test picture of a background to detect the density dispersion, estimating the degree of noise to eliminate the noise and then estimating the change of density at the areas near each point to calculate the threshold value of edge detection. CONSTITUTION:An input circuit 12 converts the picture signals supplied through a TV camera, etc. into digital pictures. A dispersion detecting circuit 13 detects the dispersion detecting circuit 13 detects the dispersion sigma of the density of the input picture signals at a background part 10. A slope distribution estimating circuit 14 estimates a distribution of density changes at the areas near each point and after elimination of noise to a picture having a density distribution corresponding to a normal distribution featured with the transmitted dispersion sigma and the prescrined mean value. An optimum threshold value setting circuit 15 calculates the minimum one of the threshold values with which the probability where the density change of the areas near each point is larger than the estimated density change is lower the level set by a level setting circuit 16 in accordance with the distribution of said estimated density change. An edge detecting circuit 20 detects a picture element point whose density slope is larger than the threshold value as the contour (edge) of an object. An edge integrating circuit 21 integrates edge signals and extracts contour lines. |
