Dynamic automatic exposure compensation for image capture devices

Abstract

The present invention describes techniques for dynamic automatic exposure compensation within image capture devices. The techniques include dynamically adjusting a default target brightness for a scene to compensate an exposure value (EV) selected by an automatic exposure process. A sensor array obtains light information from the scene at a default target brightness and an image capture controller calculates brightness values of a plurality of regions in the scene based on the light information. An automatic exposure compensation module dynamically adjusts the default target brightness based on the brightness values for the plurality of regions in the scene and threshold values set for the sensor array to set an adjusted target brightness. The sensor array may then capture an image frame of the scene using an EV for the adjusted target brightness. The techniques also include building a hysteresis zone to substantially stabilize the adjusted target brightness over a sequence of image scenes.

Description

technical field [0001] The present invention relates to capturing images with an image capture device, and more particularly to adjusting the exposure value of the image capture device. Background technique [0002] Image capture devices, such as digital video cameras or digital still cameras, are used in different applications and environments. Image capture devices should be able to produce high-quality images under a variety of lighting conditions. For example, an image capture device should be able to operate effectively in environments that include large amounts of reflected or saturated light, and in environments that include high levels of contrast. A typical image capture device performs automatic exposure to select an exposure value (EV) that achieves a certain target brightness of the scene. For example, an image capture device may select an EV that produces an image frame of a scene with an average luminance value equal to about 18% gray. [0003] The automatic...

AI Technical Summary

Problems solved by technology

However, some scenes may require higher average luminance values, while other scenes may require lower average luminance values

For example, a snowy scene includes a lot of reflected light, for which the auto-exposure process can overcompensate, thus causing the image frame to look unnaturally dark

On the other hand, a scene containing a white file next to a black laptop includes high contrast levels, for which the auto-exposure process can also overcompensate, thus causing the white file to appear fully saturated in the image frame

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