Eastman-kodak Company

Manabu Kiri

Kyoichi Omata

Toshiki Miyano

Yoshitaka Ishida

Eiichi Shimizu

A focusing device includes a movable focusing lens adapted to be moved to different positions, a conversion element for converting light incident on and transmitted through the focusing lens into a signal, and a lens driving mechanism for moving the focusing lens. The focusing device further includes a focus evaluation value calculation unit for calculating a focus evaluation value for each position of the focusing lens based on the signal from the conversion element, and a lens position specifying unit for specifying a position of the focusing lens causing a maximum focus evaluation value as an in-focus lens position. The lens driving mechanism moves the focusing lens in response to the in-focus lens position specified by the lens position specifying unit. The focus evaluation value calculation unit, in response to a plurality of observation areas, calculates a focus evaluation value through addition of partial focus evaluation values obtained for the respective observation areas, and weights the partial focus evaluation value for at least one of the plurality of observation areas on the basis of said signal to position the focusing lens.

Focusing device

The focusing lens serves to focus an image on a CCD. The image is displayed in a view finder through a different optical axis. A focus evaluation area determining circuit establishes a plurality of preset focus evaluation areas for the respective object distances on the basis of the axis offset between the optical axes of the focusing lens and the view finder. The corresponding preset object distance is compared with the object distance measured for the focus evaluation area in an object detection circuit. The result of the comparison allows the detection of an object specified in the view finder.

Object detection mechanism for imaging devices with automatic focusing

A method obtains an electrical signal from the photoelectric detector, which signal corresponds to the illumination of the image formed by the focusing lens. The image screen is divided into a plurality of subdivision areas. The method then calculates for the respective subdivision areas a focus evaluation value representative of a high frequency component contained in the electrical signal and a brightness value representative of a brightness of the image. The subdivision areas are sorted in accordance with a object distance classification. The method weights with different weights the subdivision areas on the basis of the subdivision area to which a main object belongs. Variations in the focus evaluation and brightness values are calculated by comparing the values after a focus and the values for an in-focus image. Compositional changes are detected based on the weights and the variation in the focus evaluation and brightness values.

Detecting compositional change in image

An image is divided into a plurality of subdivision areas. A focus evaluation value representative of the high frequency component contained in the electrical signal from the CCD is calculated for each of the subdivision areas. The object distance is calculated for the respective subdivision areas based on the focus evaluation value. A target object is extracted based on the calculated object distance. The target object is focused. During the focusing operation, when a new object having an object distance smaller than that of the target object is detected in any of remote subdivision areas which have an object distance larger than that of the target object, the target object is re-selected.

Method of automatic object detection in image

An automatic focusing apparatus moves a focusing lens once over a full movement range from the nearest point or from the infinite point so as to cause a photoelectric detector to output an electrical signal at predetermined stepwise lens positions. A lens position range can be specified based on the output electrical signal. The lens position range contains a lens position allowing the maximum focus evaluation value. A lens position for the maximum evaluation value is searched within the lens position range. A reliable and fast focusing operation can be obtained for finding out the maximum focus evaluation value without the effect of a local extremum in the focus evaluation value.

Automatic focusing apparatus and method

A document transport apparatus provides continuous transport of documents input with a prescribed spacing between the documents, and can rapidly detect when documents close up or overlap. Detection of close up or overlap is made by measuring a length of each document by a transported document length measuring device and comparing the measured length with a predetermined length for that document measured by an input document length measuring device positioned upstream of the transported document length measuring device. If a measured length exceeds the predetermined length, a condition of close up or overlap is deemed to exist. The document transport apparatus is described in the context of its use in an image capture apparatus or scanner.

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Machida, Japan

Manabu Kiri