Method and system in digital imaging for adjusting exposure and a corresponding device
First Claim
1. A method in digital imaging for adjusting exposure, in which one or more exposure parameters of a camera device are adjusted in connection with the imaging and in which method (i) a raw image frame corresponding to exposure parameters is captured from a camera sensor, (ii) a histogram is formed from the raw image frame, (iii) at least one characteristic value, for example, a mean value W specified in a set manner, is specified from the histogram, (iv) the characteristic value is compared with a target level set for it, (v) if the said characteristic value differs from the target level set for it according to a set criterion, the exposure parameters are adjusted in order to reach the target level and/or, (vi) a return is made to stage, characterized in that, in the method, in stage, in addition to the possibly specified mean value, one or more special values, specified in a set manner, are specified from the histogram as the said characteristic values, for which a target level, specified in a set manner, is also set, and in which for at least one characteristic value a such an offset is also specified, corrected by means of which the characteristic value, is guided towards the target level set for it, and as a result of the guiding of which one or more of the other characteristic values are guided towards the target levels set for it, and on the basis of the characteristic values and of the offsets specified for them, the said exposure parameters are then adjusted.
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Abstract
The invention relates to a method in digital imaging for adjusting exposure, in which one or more exposure parameters (ET, AG) of a camera device are adjusted in connection with imaging. In the method, a histogram formed from a raw image frame (12) is analysed, from which one or more special values (Rhigh, Rlow) are specified and which compared with a target level (Htgt, Ltgt) set for them, and, if a special value (Rhigh, Rlow) differs from the target level (Htgt, Ltgt), the exposure parameters (ET, AG) are adjusted to achieve the target level (Htgt, Ltgt).
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Citations
15 Claims
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1. A method in digital imaging for adjusting exposure, in which one or more exposure parameters of a camera device are adjusted in connection with the imaging and in which method
(i) a raw image frame corresponding to exposure parameters is captured from a camera sensor, (ii) a histogram is formed from the raw image frame, (iii) at least one characteristic value, for example, a mean value W specified in a set manner, is specified from the histogram, (iv) the characteristic value is compared with a target level set for it, (v) if the said characteristic value differs from the target level set for it according to a set criterion, the exposure parameters are adjusted in order to reach the target level and/or, (vi) a return is made to stage, characterized in that, in the method, in stage, in addition to the possibly specified mean value, one or more special values, specified in a set manner, are specified from the histogram as the said characteristic values, for which a target level, specified in a set manner, is also set, and in which for at least one characteristic value a such an offset is also specified, corrected by means of which the characteristic value, is guided towards the target level set for it, and as a result of the guiding of which one or more of the other characteristic values are guided towards the target levels set for it, and on the basis of the characteristic values and of the offsets specified for them, the said exposure parameters are then adjusted.
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14. A system in a digital imaging chain, in which the system includes a camera sensor and modular portions arranged in connection with it for processing the image data and in which, in connection with the camera sensor, there is a portion adjusting the exposure parameters, and which system is arranged to
(i) capture a raw image frame corresponding to exposure parameters from the camera sensor, (ii) form a histogram from the raw image frame, (iii) specify at least one characteristic value, for example, a mean value specified in a set manner, from the histogram, (iv) compare the characteristic value with a target level set for it, (v) if the said characteristic value differs from the target level set for it according to a set criterion, adjust the exposure parameters in order to reach the target level and/or, (vi) continue from stage (i), characterized in that, in addition to the possibly specified mean value, there are arranged to be specified from the histogram, as the said characteristic values, one or more special values, specified in a set manner, for which a target level, specified in a set manner, is also arranged to be set, and in which, for at least one characteristic value a such an offset is arranged to be defined, corrected by which the characteristic value is arranged to be guided towards the target level set for it and as a result of which guiding one or more of the other characteristic values is/are arranged to be guided towards the target values set for it, and, on the basis of the characteristic values of which and of the offsets specified for them the said exposure parameters are then arranged to be adjusted.
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15. A digital imaging device, which comprises a camera sensor and modular portions arranged in connection with it for processing the image data and in which, in connection with the camera sensor, there is a portion adjusting the exposure parameters, and which imaging device is arranged to
(i) capture a raw image frame corresponding to exposure parameters from the camera sensor, (ii) form a histogram from the raw image frame, (iii) specify at least one characteristic value, for example, a mean value specified in a set manner, from the histogram, (iv) compare the characteristic value with a target level set for it, (v) if the said characteristic value differs from the target level set for it according to a set criterion, adjust the exposure parameters in order to reach the target level and/or, (vi) continue from stage (i), characterized in that, in addition to the possibly specified mean value, there are arranged to be specified from the histogram, as the said characteristic values, one or more special values, specified in a set manner, for which a target level, specified in a set manner, is also arranged to be set, and in which, for at least one characteristic value a such an offset is arranged to be defined, corrected by which the characteristic value is arranged to be guided towards the target level set for it and as a result of which guiding one or more of the other characteristic values is/are arranged to be guided towards the target values set for it, and, on the basis of the characteristic values of which and of the offsets specified for them the said exposure parameters are then arranged to be adjusted.
Specification