Image signal processing method and image signal processing device
AssigneeKYOCERA Corporation
InventorHidetoshi Umeda
Life of this patent
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Abstract
It is possible to improve a response of a dynamic range expansion processing. The present image signal processing method includes a first step (ST2) of extracting distribution parameters from a distribution of pixel signal levels composing an image signal of one picture, a second step (ST4, ST5) of determining a target value (BP1, BP2, etc.) of a break point based on extracted distribution parameters for a break point at which an inclination of an image signal level changes with respect to a cumulative change of amount of incident light upon pixels of the imaging portion changes, and a third step (ST6, ST7) of controlling the imaging portion so as to obtain a target value and change an output saturation characteristic of the image signal.
Claims7
An image signal processing method for expanding a dynamic range of an image signal obtained from an imaging portion,
- said image signal processing method characterized by comprising
- a first step of extracting distribution parameters from a distribution of pixel signal levels composing the image signal of one picture,
- a second step of determining a target value of a break point at which an inclination of the change of image signal level with respect to a cumulative change of amount of light incident upon the pixels of the imaging portion changes on the basis of the extracted distribution parameters, and
- a third step of making an output saturation characteristic of the image signal change, by controlling the imaging portion so that the target value is obtained,
- wherein the distribution parameters include a minimum value of the pixel signal levels in the one picture,
- the target value includes a first target value indicating a maximum level of a first region having the minimum value as a starting point on the distribution,
- in the first step, an average value of the pixel signal levels of the distribution is extracted,
- in the second step, the first target value within a predetermined range about the average value is set,
- the distribution parameters include a maximum value of the pixel signal levels in the one picture, and
- in the second step, a ratio of a value obtained by subtracting the minimum value from the first target value with respect to a value obtained by subtracting the minimum value from the maximum value is found and the ratio is used to determine a second target value.
An image signal processing device for expanding a dynamic range of an image signal obtained from an imaging portion,
- said image signal processing device comprising:
- a parameter extraction portion for extracting distribution parameters from a distribution of pixel signal levels composing an image signal of one picture;
- a target setting portion for determining a target value of a break point at which an inclination of the charge of image signal level with respect to a cumulative change of amount of light incident upon the pixels of the imaging portion changes on the basis of the extracted distribution parameters, and
- a control part for of making an output saturation characteristic of the image signal change, by controlling the imaging portion so that the target value is obtained,
- wherein the distribution parameters include a minimum value of the pixel signal levels in the one picture,
- the target value includes a first target value indicating a maximum level of a first region having the minimum value as the starting point on the distribution,
- the parameter extraction portion extracts an average value of pixel signal levels of the distribution,
- the target setting portion sets the first target value within a predetermined range about the average value,
- the distribution parameters include a maximum value of pixel signal levels in the one picture, and
- the target setting portion finds a ratio of a value obtained by subtracting the minimum value from the first target value with respect to a value obtained by subtracting the minimum value from the maximum value and uses the ratio to determine the second target value.
An image signal processing device for expanding a dynamic range of an image signal obtained from an imaging portion, comprising:
- a parameter extraction portion for extracting distribution parameters from a distribution of pixel signal levels composing an image signal of one picture;
- a target setting portion for determining a target value of a break point at which an inclination of the charge of image signal level with respect to a cumulative change of amount of light incident upon the pixels of the imaging portion changes on the basis of the extracted distribution parameters, and
- a control part for of making an output saturation characteristic of the image signal change, by controlling the imaging portion so that the target value is obtained,
- wherein the distribution parameters include a minimum value of the pixel signal levels in the one picture,
- the target value includes a first target value indicating a maximum level of a first region having the minimum value as the starting point on the distribution,
- the parameter extraction portion extracts an average value of pixel signal levels of the distribution,
- the target setting portion sets the first target value within a predetermined range about the average value,
- the distribution parameters include a maximum value of pixel signal levels in the one picture, and
- the target setting portion finds a ratio of a value obtained by subtracting the minimum value from the first target value with respect to a value obtained by subtracting the minimum value from the maximum value and uses the ratio to determine the second target value.
Dependencies are inferred from the claim text.