Image sensing apparatus having automatic iris function of automatically adjusting exposure in response to video signal

Claim 2

An image sensing apparatus for automatically adjusting exposure to an object, comprising image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a target luminance level, and means (26) for changing said target luminance level according to the relation between said object evaluating value and exposure evaluating values in sampling areas other than the sampling area selected as said priority area.

Claim 3

The image sensing apparatus according to claim 1, wherein said means for changing the target luminance level comprises means for increasing said target luminance level when said object evaluating value is larger than the exposure evaluating values in the other sampling areas while decreasing said target luminance level when said object evaluating value is smaller than the exposure evaluating values in the other sampling areas.

Claim 4

The image sensing apparatus according to claim 1, wherein said target luminance level has a range defined by the upper limit and the lower limit, and said means for changing the target luminance level comprises means for changing the upper limit and the lower limit of said target luminance level according to the relation between the maximum value and the minimum value out of said exposure evaluating values and said object evaluating value.

Claim 5

The image sensing apparatus for automatically adjusting exposure to an object, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control, weighting with a predetermined ratio an exposure evaluating value in the selected sampling area with respect to exposure evaluating values in sampling areas other than the sampling area selected as said priority area and calculating an object evaluating value representing exposure of the entire image sensed picture based on the exposure evaluating values, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, and means (26) for changing said ratio according to the relation between said object evaluating value and the exposure evaluating values in the other sampling areas.

Claim 6

The image sensing apparatus for automatically adjusting exposure to an object, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control, weighting with a predetermined ratio an exposure evaluating value in the selected sampling area with respect to exposure evaluating values in sampling areas other than the sampling area selected as said priority area and calculating an object evaluating value representing exposure of the entire image sensed picture based on the exposure evaluating values, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, and means (26) for changing said ratio according to the relation between said object evaluating value and the exposure evaluating values in the other sampling areas.

Claim 7

The image sensing apparatus according to claim 4, wherein said means for changing the ratio comprises means for changing said ratio in steps according to the relation between the exposure evaluating value in the sampling area selected as said priority area and the average of the exposure evaluating values in all the sampling areas.

Claim 8

The image sensing apparatus according to claim 4, wherein said means for changing the ratio comprises means for continuously changing said ratio according to the relation between the exposure evaluating value in the sampling area selected as said priority area and the average of the exposure evaluating values in all the sampling areas.

Claim 9

The image sensing apparatus for automatically adjusting exposure to an object, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, means (26) for comparing the exposure evaluating value supplied from said exposure evaluating value calculating means with a predetermined reference value, to replace the exposure evaluating value with a predetermined fixed value when said exposure evaluating value is smaller than said reference value, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, and exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level.

Claim 10

The image sensing apparatus for automatically adjusting exposure to an object, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, means (26) for comparing the exposure evaluating value supplied from said exposure evaluating value calculating means with a predetermined reference value, to replace the exposure evaluating value with a predetermined fixed value when said exposure evaluating value is smaller than said reference value, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, and exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level.

Claim 11

The image sensing apparatus according to claim 7, wherein said fixed value is determined based on a value at which the effect of the change of the exposure evaluating value caused by noises on exposure control can be recognized.

Claim 12

An image sensing apparatus for automatically adjusting exposure to an object and automatically performing gamma correction of a video signal, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, means (26) for calculating a value indicating the contrast of the image sensed picture based on the exposure evaluating values supplied from said exposure evaluating value detecting means, means (26) for determining a gamma correction value based on said value indicating the contrast to perform gamma correction of said video signal according to the gamma correction value, and means (26) for changing said gamma correction value according to the relation between said object evaluating value and exposure evaluating values in the sampling areas other than the sampling area selected as said priority area.

Claim 13

An image sensing apparatus for automatically adjusting exposure to an object and automatically performing gamma correction of a video signal, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, means (26) for calculating a value indicating the contrast of the image sensed picture based on the exposure evaluating values supplied from said exposure evaluating value detecting means, means (26) for determining a gamma correction value based on said value indicating the contrast to perform gamma correction of said video signal according to the gamma correction value, and means (26) for changing said gamma correction value according to the relation between said object evaluating value and exposure evaluating values in the sampling areas other than the sampling area selected as said priority area.

Claim 14

An image sensing apparatus for automatically adjusting exposure to an object and automatically performing gamma correction of a video signal, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, means (26) for calculating a value indicating the contrast of the image sensed picture based on the exposure evaluating values supplied from said exposure evaluating value detecting means, and means (26) for determining a gamma correction value based on said value indicating the contrast to perform gamma correction of said video signal according to the gamma correction value.

Claim 15

An image sensing apparatus for automatically adjusting exposure to an object and automatically performing gamma correction of a video signal, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, means (26) for calculating a value indicating the contrast of the image sensed picture based on the exposure evaluating values supplied from said exposure evaluating value detecting means, and means (26) for determining a gamma correction value based on said value indicating the contrast to perform gamma correction of said video signal according to the gamma correction value.

Claim 16

An image sensing apparatus for automatically adjusting exposure to an object and automatically performing gamma correction of a video signal, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, means (26) for determining a gamma correction value to perform gamma correction of said video signal according to the gamma correction value, and means (26) for changing said gamma correction value according to the relation between said object evaluating value and exposure evaluating values in the sampling areas other than the sampling area selected as said priority area.

Claim 17

An image sensing apparatus for automatically adjusting exposure to an object and automatically performing gamma correction of a video signal, comprising: image sensing means (2, 8) having a lens and an image sensor for generating a video signal in response to light incident from said object, means (6, 7, 301) for changing exposure to said object, means (12, 13, 15) for setting a plurality of sampling areas divided on an image sensed picture in a time-divisional manner of said video signal, exposure evaluating value detecting means (11, 16-21) for detecting a level of a luminance signal in a video signal in each of said plurality of sampling areas, to supply the same as an exposure evaluating value in the corresponding sampling area, object evaluating value calculating means (26) for selecting at least one of said plurality of sampling areas as a priority area for exposure control and calculating an object evaluating value representing exposure of the entire image sensed picture based on an exposure evaluating value in the selected sampling area, exposure control means (26, 28) for controlling said exposure changing means such that said object evaluating value approaches a predetermined target luminance level, means (26) for determining a gamma correction value to perform gamma correction of said video signal according to the gamma correction value, and means (26) for changing said gamma correction value according to the relation between said object evaluating value and exposure evaluating values in the sampling areas other than the sampling area selected as said priority area.