Image capturing apparatus to prevent image blurring and control method therefor

Abstract

An image capturing apparatus includes a motion vector detection unit which detects a motion vector on the basis of the correlation between image signals continuously captured by an image capturing unit, a reliability evaluation value calculation unit which calculates the reliability evaluation value of the motion vector detected by the motion vector detection unit, a blurring correction amount determination unit which determines the image blurring correction amount on the basis of the motion vector detected by the motion vector detection unit, a correction amount reduction unit which reduces the image blurring correction amount on the basis of the reliability evaluation value calculated by the reliability evaluation value calculation unit, and a blurring correction unit which corrects image blurring on the basis of the image blurring correction amount reduced by the correction amount reduction unit.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a technique of detecting the motion vector of a moving image to correct blurring of the moving image.[0003]2. Description of the Related Art[0004]An image capturing apparatus such as a video camera which captures a moving image suffers image blurring owing to camera shake when the lens zooms to the telephoto end. To prevent image blurring caused by camera shake, there has conventionally been proposed a technique of detecting the motion vector of an image from a captured image signal and correcting image blurring on the basis of the motion vector.[0005]Known examples of the conventional method of detecting the motion vector of a moving image are a correlation method based on correlation calculation, and block matching.[0006]According to block matching, an input image signal is divided into a plurality of blocks (e.g., eight pixels×eight lines) of a proper size. Differences from pixels in ...

AI Technical Summary

Benefits of technology

[0021]The present invention has been made to overcome the conventional drawbacks, and has as its object to suppress the discontinuity of the blurring correction effect in a moving image.

[0022]To solve the above-described problems and achieve the above-described object, according to the first aspect of the present invention, there is provided an image capturing apparatus comprising an image capturing unit which captures an object image formed by an imaging optical system and outputs an image signal, a motion vector detection unit which detects a motion vector on the basis of correlation between image signals continuously captured by the image capturing unit, a reliability evaluation value calculation unit which calculates a reliability evaluation value of the motion vector detected by the motion vector detection unit, a blurring correction amount determination unit which determines an image blurring correction amount on the basis of the motion vector detected by the motion vector detection unit, a correction amount reduction unit which reduces the image blurring correction amount in accordance with a reduction rate determined based on the reliability evaluation value calculated by the reliability evaluation value calculation unit, and a blurring correction unit which corrects image blurring on the basis of the image blurring correction amount reduced by the correction amount reduction unit.

Problems solved by technology

An image capturing apparatus such as a video camera which captures a moving image suffers image blurring owing to camera shake when the lens zooms to the telephoto end.

However, according to the conventional technique, if it is determined that the number of valid motion vectors is smaller than a predetermined value, i.e., the reliability of detected motion vectors is poor, the motion vectors are invalidated not to execute blurring correction.

However, when an image has few characteristic patterns or includes many similar features, a motion vector of low reliability is detected.