Method and control unit for controlling exposure of a camera
AssigneeAxis AB
InventorsFredrik Svensson, Johan Tuvesson, Linda Haals
Life of this patent
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Abstract
A method for controlling exposure of a camera is disclosed. The method comprises calculating a darkness level and a saturation level with respect to a first image in a video sequence. If the saturation level exceeds a first limit, a target value for a mean intensity value of pixels in images captured by the camera is decreased by an amount which is an increasing function of the darkness level. The decreased target value is used to control the exposure of the camera for images subsequent to the first image in the video sequence, such that the mean intensity value of pixels in the subsequent images approaches the decreased target value.
Claims15
A method for controlling exposure of a camera, comprising:
- determining an exposure time and a gain used by the camera when capturing a first image in a video sequence;
- calculating a darkness level with respect to the first image as a product of at least the exposure time and the gain;
- calculating a saturation level with respect to the first image as a ratio between a number of saturated pixels and a number of completely dark pixels in the first image;
- if the saturation level exceeds a first limit, decreasing a target value for a mean intensity value of pixels in images captured by the camera by an amount which is an increasing function of the darkness level;
- and
- controlling exposure of the camera for images subsequent to the first image in the video sequence, such that the mean intensity value of pixels in the subsequent images approaches the decreased target value.
A control unit for controlling exposure of a camera, the control unit configured to:
- determine an exposure time and a gain used by the camera when capturing a first image in a video sequence;
- calculate a darkness level with respect to the first image as a product of at least the exposure time and the gain;
- calculate a saturation level with respect to the first image as a ratio between a number of saturated pixels and a number of completely dark pixels in the first image;
- if the saturation level exceeds a first limit, decrease a target value of a mean intensity value of pixels in images captured by the camera by an amount which is an increasing function of the darkness level;
- and
- control exposure of the camera for images subsequent to the first image in the video sequence such that the mean intensity value of pixels in the subsequent images approaches the decreased target value.
Dependencies are inferred from the claim text.