Automatic exposure method based on histogram equalization

A technology of histogram equalization and automatic exposure, applied in the control of exposure, optics, image communication, etc., can solve problems such as overexposure and underexposure of the subject, and achieve the effect of small data processing

Inactive Publication Date: 2012-06-27
NORTHWESTERN POLYTECHNICAL UNIV +1
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0009] In order to solve the technical problem of underexposure or overexposure of the subject in t...

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  • Automatic exposure method based on histogram equalization
  • Automatic exposure method based on histogram equalization

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Embodiment Construction

[0024] Such as figure 1 As shown, the automatic exposure method based on histogram equalization includes the following steps:

[0025] 1] Collect a frame of image and record the exposure time t of the frame old ;

[0026] 2] Calculate the brightness mean value m(Y) of the collected image;

[0027] 3] Perform histogram equalization processing on the collected images;

[0028] 4) Calculating the brightness mean value Yt of the image processed by the histogram equalization;

[0029] 5] Calculate the exposure time t of the next frame new , according to the formula t new = t old *(Y t / m(Y)) (the exposure time is proportional to the average brightness of the image)

[0030] 6] if|t new -t old |new = t old , continue to step 1];

[0031] If|t new -t old |>δ, indicating that the exposure time of the two frames before and after is quite different, and the exposure time of the next frame needs to be set according to the new exposure time t new Adjust, continue to step 1]...

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Abstract

The invention relates to an automatic exposure method based on histogram equalization, which includes steps of acquiring a frame image, recording exposure time of a frame, computing average value of the brightness of the acquired frame image, performing histogram equalization on the acquired frame image, computing average value of gray level of the image after the histogram equalization, computing exposure time of the next frame according to the principle that the exposure time is in direct proportion to the average value of the brightness of the image, setting exposure adjustment tolerance and the like. By the aid of the automatic exposure method, the technical problems of insufficient exposure or overexposure of a pickup body in the prior art are solved, the average value of the gray level of the image after histogram equalization is used as the optimum average value which can reflect characteristics of the brightness of the image sufficiently and is dynamic and can be suitable for environments with various brightness.

Description

technical field [0001] The invention relates to an automatic exposure method based on histogram equalization. Background technique [0002] The exposure method adopted by the camera can be either metered manual exposure or automatic exposure. [0003] Metering manual exposure is an exposure method in which the photographer chooses the aperture factor and shutter speed, and uses the camera's metering system to determine whether the exposure is appropriate. [0004] Automatic exposure is an exposure method in which the camera automatically selects the aperture factor and shutter speed according to the metering results of its own metering system to obtain accurate exposure. Automatic exposure can be divided into aperture priority automatic exposure, shutter priority automatic exposure, program automatic exposure and other forms. [0005] Aperture-priority automatic exposure means that the aperture factor is selected artificially, and the camera automatically selects the shutt...

Claims

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Application Information

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IPC IPC(8): H04N5/235G03B7/08
Inventor 闫荣华陈荣利汶德胜高伟张蕴奇
Owner NORTHWESTERN POLYTECHNICAL UNIV
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