Determining a final exposure setting automatically for a solid state camera without a separate light metering circuit

Claim 3

The method of claim 1 wherein the captured scene is grossly under or overexposed if (1) there are few pixels in the captured scene, using the current exposure setting, that have at least a noise value, or (2) there are many pixels in the captured scene that have a maximum value.

Claim 4

The method of claim 1 wherein the captured scene is overexposed if an average value of pixels in a histogram of a portion of the captured scene is greater than an aim mean value.

Claim 5

The method of claim 3 wherein the aim mean value includes a noise value representing noise in an imaging data path of the camera imager.

Claim 6

The method of claim 4 wherein the noise value is computed as a function of one or more exposure parameters that define the current exposure setting, the function being determined by analyzing pixel values in a plurality of dark frame portions captured by the solid state camera under different exposure settings to determine a mathematical relationship between a noise variable and one or more exposure parameter variables.

Claim 7

The method of claim 5 wherein the function is determined upon camera power-up and is used to compute the noise value in subsequent captured scenes.

Claim 8

The method of claim 1 wherein the plurality of exposure settings are arranged in a monotonic sequence.

Claim 9

The method of claim 7 wherein the search methodology performs the binary chop so long as (1) there are few pixels in the captured scene, using the current exposure setting, that have at least a noise value, or (2) there are many pixels in the captured scene that have a maximum value, and otherwise steps to an adjacent setting from the current exposure setting when selecting another one of the exposure settings.

Claim 10

The method of claim 1 wherein each exposure setting is in part defined by a set of exposure parameters for the camera, the exposure parameters including a gain applied in the imagining data path.

Claim 11

The method of claim 9 wherein the gain is applied to analog pixel signals prior to their being digitized.

Claim 12

The method of claim 1 wherein each exposure setting is in part defined by a set of exposure parameters for the camera, the exposure parameters including a pixel integration time.

Claim 13

The method of claim 1 wherein in d), the captured scene is neither underexposed or overexposed if an average pixel value in the captured scene is a percentage of a maximum digital output value of an A/D converter less a value expected for noise in an average pixel, plus the value expected for noise.

Claim 14

An electronic camera comprising: camera imager to provide pixel values defining a captured scene using an exposure setting; and processing electronics to automatically generate a final exposure setting without using a light metering circuit separate from the camera imager, wherein for a current exposure setting selected from a plurality of predetermined exposure settings that are arranged from the one corresponding to the least exposure to the one corresponding to the greatest exposure, a) the camera imager is to provide pixel values defining the captured scene using the current setting, and b) the processing electronics is to select according to an automated search methodology another one of the plurality of exposure settings to be the current setting in response to the captured scene being underexposed or overexposed, and wherein a) and b) are to repeat until the current exposure setting is neither underexposed or overexposed as determined using the pixel values defining the captured scene, where the automated search methodology is to perform a binary chop of the exposure settings so long as the captured scene is either grossly overexposed or grossly underexposed, and then changes to a fine granularity search if the captured scene is still overexposed or underexposed but not grossly so.

Claim 15

An electronic camera comprising: camera imager to provide pixel values defining a captured scene using an exposure setting; and processing electronics to automatically generate a final exposure setting without using a light metering circuit separate from the camera imager, wherein for a current exposure setting selected from a plurality of predetermined exposure settings that are arranged from the one corresponding to the least exposure to the one corresponding to the greatest exposure, a) the camera imager is to provide pixel values defining the captured scene using the current setting, and b) the processing electronics is to select according to an automated search methodology another one of the plurality of exposure settings to be the current setting in response to the captured scene being underexposed or overexposed, and wherein a) and b) are to repeat until the current exposure setting is neither underexposed or overexposed as determined using the pixel values defining the captured scene, where the automated search methodology is to perform a binary chop of the exposure settings so long as the captured scene is either grossly overexposed or grossly underexposed, and then changes to a fine granularity search if the captured scene is still overexposed or underexposed but not grossly so.

Claim 16

An electronic camera according to claim 13 wherein the processing electronics is to initially select another one of the exposure settings with coarse granularity if (1) there are relatively few pixels in the captured scene, using the current exposure setting, that have a substantial value, or (2) there are many pixels in the captured scene that have a maximum value, and then with fine granularity until the captured scene is neither underexposed or overexposed as determined using the pixel values.

Claim 17

An electronic camera according to claim 13 wherein the search methodology performs the binary chop so long as (1) there are few pixels in the captured scene, using the current exposure setting, that have at least a noise value, or (2) there are many pixels in the captured scene that have a minimum or a maximum value, and otherwise performs a step to an adjacent setting from the current exposure setting when selecting another one of the exposure settings.

Claim 18

An electronic camera according to claim 13 wherein the processing electronics is to determine that the captured scene is underexposed if an average value of pixels in a histogram of a portion of the captured scene is less than an aim mean value.

Claim 19

An electronic camera according to claim 16 wherein the aim mean value is computed as a function of one or more exposure parameters that define the current exposure setting.

Claim 20

An electronic camera according to claim 17 wherein the function is determined by analyzing pixel values in a plurality of dark frame portions captured by the solid state camera under different exposure settings to determine a mathematical relationship between a noise variable and one or more exposure parameter variables.

Claim 21

An electronic camera according to claim 13 wherein the camera imager includes an image sensor array and associated analog and digital signal processing circuitry that provide the pixel values.

Claim 22

An electronic camera according to claim 19 wherein the image sensor array and the associated signal processing circuitry are integrated on the same semiconductor die.

Claim 23

An electronic camera according to claim 13 wherein the processing electronics includes a processor and memory containing instructions which when executed by the processor cause the automatic generation of the optimal exposure setting.

Claim 24

An article of manufacture comprising a machine-readable medium having a plurality of instructions therein which when executed by a processor cause an electronic system to a) select one of a plurality of exposure settings as a current exposure setting for a solid state camera having a camera imager; b) receive a captured scene obtained by the camera imager using the current exposure setting; c) select according to an automated search methodology another one of the exposure settings to be the current setting in response to the captured scene being underexposed or overexposed; and d) repeat b) and c) until the captured scene is neither underexposed or overexposed, wherein the search methodology performs a binary chop so long as the captured scene is either grossly overexposed or grossly underexposed, and then changes to a fine granularity search if the captured scene is still overexposed or underexposed but not grossly so.

Claim 25

An article of manufacture comprising a machine-readable medium having a plurality of instructions therein which when executed by a processor cause an electronic system to a) select one of a plurality of exposure settings as a current exposure setting for a solid state camera having a camera imager; b) receive a captured scene obtained by the camera imager using the current exposure setting; c) select according to an automated search methodology another one of the exposure settings to be the current setting in response to the captured scene being underexposed or overexposed; and d) repeat b) and c) until the captured scene is neither underexposed or overexposed, wherein the search methodology performs a binary chop so long as the captured scene is either grossly overexposed or grossly underexposed, and then changes to a fine granularity search if the captured scene is still overexposed or underexposed but not grossly so.

Claim 26

An article of manufacture according to claim 23 wherein the fine granularity search includes a step from the current exposure setting.

Claim 27

An article of manufacture according to claim 22 wherein the captured scene is grossly under or overexposed if (1) there are few pixels in the captured scene, using the current exposure setting, that have at least a noise value, or (2) there are many pixels in the captured scene that have a maximum value.

Claim 28

An article of manufacture according to claim 22 wherein the captured scene is overexposed if an average value of pixels in a histogram of a portion of the captured scene is greater than an aim mean value.

Claim 29

An article of manufacture according to claim 25 wherein the aim mean value includes a noise value representing noise in an imaging data path of the camera imager.

Claim 30

An article of manufacture according to claim 26 wherein the noise value is computed as a function of one or more exposure parameters that define the current exposure setting, the function being determined by analyzing pixel values in a plurality of dark frame portions captured by the solid state camera under different exposure settings to determine a mathematical relationship between a noise variable and one or more exposure parameter variables.

Claim 31

An article of manufacture according to claim 27 wherein the function is determined upon camera power-up and is used to compute the noise value in subsequent captured scenes.

Claim 32

An article of manufacture according to claim 23 wherein the search methodology performs the binary chop so long as (1) there are few pixels in the captured scene, using the current exposure setting, that have at least a noise value, or (2) there are many pixels in the captured scene that have a maximum value, and otherwise steps to an adjacent setting from the current exposure setting when selecting another one of the exposure settings.

Claim 33

An article of manufacture according to claim 22 wherein each exposure setting is in part defined by a set of exposure parameters for the camera, the exposure parameters including a gain applied in the imaging data path.

Claim 34

An article of manufacture according to claim 30 wherein the gain is applied to analog pixel signals prior to their being digitized.

Claim 35

An article of manufacture according to claim 22 wherein each exposure setting is in part defined by a set of exposure parameters for the camera, the exposure parameters including a pixel integration time.

Claim 36

An article of manufacture according to claim 22 wherein in d), the captured scene is neither underexposed or overexposed if an average pixel value in the captured scene is a percentage of a maximum digital output value of an A/D converter less a value expected for noise in an average pixel, plus the value expected for noise.