Automatic exposure control method and device for digital video camera

Abstract

The present invention discloses an automatic exposure control method of a digital camera and a device. Based on the method, when a target subject is detected in an image, brightness control information is generated according to target subject average brightness, the imaging effect of the target subject can be ensured pointedly, when the target subject is not detected in the image, brightness control information is generated according to a whole frame average brightness and the first weighted value of a whole frame calibration brightness, since the weighted proportion of the whole frame average brightness in the first weighted value and the frame cumulative value of target subject continuous detection failures are in a monotonically increasing relationship, when the target subject has a fluctuation phenomenon sometimes in the multiple continuous frames of images, the first weighted value is changed in a gradual manner and does not change suddenly, thus the transition amplitude of the brightness control information can be weakened, and thus the brightness smoothness and birghtness stability of exposure are improved.

Description

technical field [0001] The invention relates to exposure technology, in particular to an automatic exposure control method for a digital camera and an automatic exposure control device for a digital camera. Background technique [0002] Exposure is one of the most important links in the working process of a digital camera, that is, the process in which the photosensitive element of the digital camera receives light signals, senses electrical signals, and stores electrical signals. As we all know, the longer the shutter time, the more light signals received by each pixel unit of the photosensitive element, and the more electrical signals are sensed and stored, so the brightness of the corresponding pixel points formed in the image is also higher. Conversely, the shorter the shutter time, the lower the brightness of each pixel unit of the photosensitive element at the corresponding pixel point formed in the image. In addition, in addition to the shutter, gain and aperture ape...

AI Technical Summary

Problems solved by technology

[0017] (1) Due to the existence of random factors such as the movement of the target subject or detection omissions, there may be occasional fluctuations of the target subject in continuous multi-frame images, so there may be continuous jumps in the value of the brightness control information Changes, resulting in poor brightness smoothness and brightness stability of exposure;

[0018] (2) Since the control of exposure only depends on the average brightness of the target subject, when there is a sudden change in the brightness of the shooting environment (such as turning on or off the light, etc.), and the sudden change in brightness prevents the target subject from being successfully detected, it is impossible to pass the adjustment The luminous flux makes the brightness of the image adapt to the brightness after the mutation, which leads to the continuous failure of the detection of the target subject;

[0019] (3) Even if there is no sudden change in brightness, due to slight light changes in the shooting environment or changes in the angle of the target subject relative to the camera, the average brightness of the same target subject may fluctuate in consecutive multiple frames of images. And such brightness fluctuation will cause the value of brightness control information to fluctuate accordingly, and then affect the brightness smoothness and brightness stability of exposure;

[0020] (4), when the target subject is not detected in the image, the exposure mode for the target subject is still maintained, and the overall brightness of the image cannot be taken into consideration;

[0021] (5) For the situation where there are multiple target subjects in the image, there is no calculation method for determining the brightness control information based on the average brightness of the target subjects of multiple target subjects

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