Canon Kabushiki Kaisha

Hideo Homma

Kunihiko Yamada

Akihiro Fujiwara

Kitahiro Kaneda

Hirofumi Suda

Hisashi Ishikawa

Katsuji Yoshimura

Masamichi Toyama

Takashi Saito

Yoshitake Nagashima

Kunio Imai

Teruo Hieda

An exposure control device having a light measuring area setting circuit which sets a light measuring area on an image sensing plane, a discriminating circuit which discriminates from each other varied states of the image sensing plane through video signal parts corresponding to the inside and the outside of the light measuring area and an exposure compensating circuit which compensates the state of exposure to light is arranged to shift the set position of the light measuring area to trace an object's image at least when the exposure compensating circuit is in operation. The operating modes of the device includes a first light measuring mode in which a quantity of light is measured on the basis of the average video signal level of the whole image sensing plane, a second light measuring mode in which the light quantity is measured with weight attached to a video signal part obtained from the inside of the light measuring area, and a third light measuring mode in which the light quantity is measured with weight attached to the video signal of the light measuring area by shifting the light measuring area to trace the object. The three light measuring modes are adaptively switched from one over to another.

Exposure control device

An exposure control device includes a first exposure control circuit which is arranged to keep constant an average signal level of an image signal corresponding to the whole of an image sensing plane, and a second exposure control circuit which is arranged to compensate the average signal level according to the level of an image signal corresponding to a light measuring area set in a part of the image sensing plane. The second exposure control circuit has a response characteristic arranged to have its exposure control action performed at a slower response speed than the first exposure circuit.

Video camera apparatus having an exposure control device

An exposure control device for performing exposure control on the basis of a video signal obtained from a light measuring area set within an image sensing plane is provided with a determining circuit which determines the position of a photographed object within the image sensing plane from the values of a specific component of the video signal obtained from the inside and outside of a detection area the position of which is variably set within the image sensing plane. The light measuring area is set in the object's position within the image sensing plane detected by the determining circuit. The exposure control device is provided further with a changing circuit which detects the size of the object on the image sensing plane and changes the size of the light measuring area accordingly, and a weighting circuit which performs for light measurement a weighting operation on video signals obtained from the inside and outside of the light measuring area.

An image processing apparatus has a memory device for storing pixel image data including both halftone image data such as data of image of a photograph having a gradation and line image data such as data of text containing characters. The storage is conducted on the basis of blocks each having a predetermined number of pixels. The mean information quantity of the halftone image data per pixel stored in the memory means is not greater than the information quantity of the line image data per pixel stored in the memory means. The halftone image data being compressed on the basis of the block. Therefore, both the halftone image data and line image data can be stored in a small memory by using common addresses, without causing any degradation of the image quality.

Image processing apparatus

Exposure control device having a plurality of light detecting areas

An exposure control device includes an area setting circuit which sets a light measuring area on a part of an image sensing plane; a judging circuit which detects a back light image plane on the basis of a difference in level between video signals corresponding to the inside and the outside of the light measuring area; a high luminance detecting circuit which detects a high luminance part of the image sensing plane on the basis of the video signals; and a control circuit arranged to have the light measuring area set on the image sensing plane excluding the high luminance part from the light measuring area by controlling the area setting circuit on the basis of the output of the high luminance detection circuit when the image sensing plane is judged to be a back light image plane by the judging circuit. The device is arranged to attach weight to the average levels of the signals of the inside and the outside of the light measuring area according to the result of comparison of these signals, to add the weighted average signal levels together and to perform exposure control according to the result of addition.

Automatic exposure control device with light measuring area setting

An image sensing apparatus operating with adaptive selection of a first tracing algorithm in which an object image is traced by moving a detecting area capable of being movably set on an image sensing plane in such a manner that the luminance level difference between the inside and the outside of that area becomes maximum and a second tracing algorithm in which the object image is traced by moving the position of the detecting area in such a manner that a point at which a contrast becomes maximum comes to coincide with a central portion of the detecting are depending on the state of the image sensing plane. The threshold values for changing over between the first tracing algorithm and the second tracing algorithm are made to have a hysteresis characteristic.

Image sensing apparatus

Automatic exposure control device using plural image plane detection

An image processing apparatus has a memory device for storing pixel image data, including both halftone image data such as data of image of a photograph having a gradation, and line image text data such as data, containing characters. The storage is conducted on the basis of blocks each having a predetermined number of pixels. The mean information quantity of the halftone image data per pixel stored in the memory means is not greater than the information quantity of the line image data per pixel stored in the memory means. The halftone image data is compressed on the basis of blocks. Therefore, both the halftone image data and line image data can be stored in a small memory by using common addresses, without causing any degradation of the image quality.

An image pickup apparatus for outputting an image pickup signal by forming an image of a subject on an image pickup element through an optical system includes a determining circuit for picking up a plurality of color information signals from the image pickup element, comparing the color information signals with a predetermined reference value to determine that the color information signals reach a predetermined level and detecting quantity of a skin color signal component; and a control circuit for controlling the exposure of the image pickup element in accordance with the result of the determination.

Image pickup apparatus having exposure control for human subjects

An image sensing device allowing normal or teleconversion operation has an image sensor which includes a plurality of horizontal lines and is capable of being non-destructively read out. Area setting ciruitry is included for variably setting a reading area of the image sensor. Clock control circuitry includes a plurality of reading lines and is arranged to read out image information from the selected reading area. Reading circuitry non-destructively reads out, a plurality of times for the tele-conversion operation, the signals from the set reading area. The reading cycle corresponds to the size of the set reading area. Clearing circuitry is also included for clearing altogether the areas of the image sensor other than the set reading area.

Growing community of inventors

Tokyo, Japan

Hideo Homma