| 摘要 |
PURPOSE:To obtain the position of the end-faces of an object to be detected in the same section, by converting the level of sensitivity of a video input device into a digital gradation data comprising plural bits and obtaining the section during which the data of the digital gradation data increases or decreases consecutively. CONSTITUTION:A rustry round steel 1 has about 100 diameter and length, and the visually recognized positions are shown in the figure for the white lusterless paper and a photodetector 3. The threshold level is determined to obtain the positions of edges E1 and E2. The minimum level of the image concentration is set at binary number 0000 for a gradation data of 4 bits to be increased to 0001, 0010- as the image concentration increases. The figures written along the signal lines show the differential coefficients between the adjacent point and the digital signal value at each spot on the x axis. The edges E1 and E2 exist in the section in which the differential coefficient of the same code is continuous. Thus it is supposed that the left edge E1 and the right edge E2 are set at positions (x2-x1)/2 and (x4-x3)/2 respectively. In such way, the positions of the E1 and E2 are obtained. |
