Hitachi Industry & Control Solutions, Ltd.

Iori Umezawa

Tomoaki Nishiguchi

Hideharu Ono

Toshiyuki Yokoyama

Yukitoshi Shirota

Toshifumi Inokuchi

A change in a subject is quickly sensed and a focusing lens is driven with degradation in durability and out-of-focus states of output video images due to driving of the focusing lens more than necessary avoided. To achieve the object described above, the invention relates to an imaging apparatus that controls a focusing lens based on a contrast signal provided from a video signal and includes a controller that performs first evaluation based on comparison between the value of the contrast signal and the value of a main threshold, performs second evaluation after the first evaluation based on comparison between the value of the contrast signal and a sub-threshold that is greater or smaller than the main threshold and is set to decrease or increase with the lapse of time, and performs focus control on the focusing lens based on a result of the second evaluation.

Apparatus, imaging method, and focus control apparatus to control autofocus based on contrast signal

A focus control apparatus that achieves a focused state even when a subject is a point light source includes a contrast signal generator that divides a captured image screen into a plurality of areas, extracts a frequency component based on a video signal for each of the divided areas, and generates a first contrast signal based on the frequency component. A controller extracts a luminance intensity based on the video signal for each of the divided areas, determines, for each of the divided areas, a second contrast signal generated by increasing or decreasing the magnitude of the first contrast signal from the divided area based on the magnitude of the luminance intensity, determines a lens position evaluation value that is the sum of the second contrast signals, and performs the focus control based on the lens position evaluation value.

Focus control apparatus and method

A focus control apparatus reduces the degree of out-of-focus of an image of an intense point light source during zooming in contrast-based autofocus control. A zooming lens moves in an optical axis direction to perform magnification change and a focusing lens moves in the optical axis direction to perform focus adjustment and is driven in accordance with a trace curve corresponding to the distance to a subject. A controller evaluates, during the magnification change operation, based on the rate of change in the number of high-luminance pixels at which the number of high-luminance pixels in an output image from the imaging apparatus changes with the zoom magnification, whether or not the focusing lens is driven in accordance with a trace curve corresponding to the distance to the subject before the magnification change operation is performed or a trace curve corresponding to a distance to the subject of infinity.

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Tokyo, Japan

Iori Umezawa