US 4,904,855 AGranted

Method for detecting relative position of an image pair including contrast detection

AssigneeFuji Electric Co., Ltd.

InventorsTakashi Nishibe, Shotaro Yokoyama

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Abstract

A method and system for finding an exact focus of a taking lens of a single lens camera or the like. The method detects the relative position between two images on the basis of light intensity distribution of the images from a pair of light sensor arrays that receive the images through light paths separated from each other in space. The relative position depends on whether a taking lens of a camera is in front-focus condition or in back-focus condition. Partial image data consisting of n data respectively are sampled from the two image data as verification data. A number of combinations of the data are used to calculate evaluation values indicative of the level of correlation between the respective verification data. Correct focus exhibits the highest correlation. The method overcomes the problem that the combination having the highest correlation may not be correctly determined due to abnormal shape or envelope of the plotted distribution of the evaluation value.

Claims8

Dependent claims

A method for detecting the relative position of images incident upon a pair of optical sensor arrays on the basis of a pair of image data, the pair of image data comprising a plurality of data indicative of light intensity distribution of the images, the image data being output from a pair of optical sensor arrays that receive the images through separate light paths in space, the method comprising the steps of:

sampling a portion of at least one of the pair of image data and forming a plurality of combinations of verification data comprising a predetermined number of adjacent data on each optical sensor array;
calculating an evaluation value indicative of the correlation between the verification data for every combination formed;
detecting the amount of variation in the respective verification data and determining whether the data is of low contrast when the amount of variation in at least one of the two verification data within the respective combination is smaller than a predetermined limit;
correcting the evaluation value of the combination of verification data which has been determined to be of low contrast to a value indicative of low correlation;
selecting a combination in which the verification data indicates the highest correlation from the plurality of combinations of verification data by using the corrected evaluation value, wherein the relative position of the images on the optical sensor arrays is detected on the basis of the number indicative of the combination selected.

2 more elements

A system for detecting the relative position of images incident upon a pair of optical sensor arrays on the basis of a pair of image data, the pair of image data comprising a plurality of data indicative of light intensity distribution of the images, the image data being output from a pair of optical sensor arrays that receive the images through separate light paths in space, comprising:

combining means for sampling a portion of at least one of the pair of image data and forming a plurality of combinations of verification data comprising a predetermined number of adjacent data on each optical sensor array;
calculation means for calculating an evaluation value indicative of the correlation between the verification data for every combination formed;
decision making means for detecting the amount of variation in the respective verification data and determining whether the data is of low contrast when the amount of variation in at least one of the two verification data within the respective combination is smaller than a predetermined limit;
correction means for correcting the evaluation value of the combination of verification data which has been determined to be of low contrast to a value indicative of low correlation;
selection means for selecting a combination in which the verification data indicates the highest correlation from the plurality of combinations of verification data by using the corrected evaluation value, wherein the relative position of the images on the optical sensor arrays is detected on the basis of the number indicative of the combination selected.

2 more elements

Dependencies are inferred from the claim text.