| 摘要 |
PURPOSE:To improve considerably the sensitivity and accuracy of focusing, by noticing only the parts before and after the focusing where an abrupt change arises, using plural sets of sampling points and constituting an evaluation function. CONSTITUTION:An input image (g) is in the state of (c) in the stage of focusing. It is evident from the figures that the changes in the output difference between the positions A and B and the output difference between C and D are most significant in the change in sensor output with changes in a-f. Therefore, if an evaluation function f(X) is constituted as f(X)=(XA-XB)+(XC-XD), the output change can be detected with the highest sensitivity. The sampling points to be utilized are plural and the resistance to noise is improved. In actuality, the output from an image sensor is processed; therefore, if the value obtd. by subtracting the min. value from the max. value of the adjacent output differences is determined as the evaluation function, the conditions of the following equations hold. |
