| 摘要 |
PURPOSE:To improve the detecting speed of the angle difference between two similar pictures, by compressing the angle histogram data of the density gradient of the picture element value of a picture and reducing the calculating quantity. CONSTITUTION:The density data of each picture element constituting a picture to be collated are recorded in an image memory 1 and the maximum changing direction of the picture element density is found by a space differentiating circuit 2 composed of a 3X3 differentiation calculating window. Then the angle histogram of the density gradient is produced by a histogram calculating circuit 3. After the change by angle of the angle histogram is averaged by means of a smoothing circuit 4, feature quantities of the histogram, such as the differ ence between adjacent maximum and minimum, their angle difference, etc., are extracted and the data quantity is compressed by a feature extracting circuit 5. Thereafter, the data are shifted by a shifting circuit 7 and compared with similar data of a reference picture stored in a reference feature memory 6 at a distance calculating circuit 8 and an angle is found. |
