Method for adaptively adjusting exposure and contrast of human eye iris image
An adaptive adjustment and iris image technology, applied in image enhancement, image analysis, image data processing, etc., can solve the problems of inconsistency and inconsistency of iris images, achieve good real-time contrast and avoid deviation effects
Active Publication Date: 2020-12-04
FOCTEK PHOTONICS LNC
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[0003] However, for the same camera equipment, the iris images collected under different ambient brightness are not consistent, and the iris brightness of different collected objects is also different, that is, it is difficult to adjust a set of exposure and contrast parameters to meet the image requirements of all the iris of the measured subjects
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[0032] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.
[0033] A kind of method that the present invention proposes to human iris image exposure and contrast self-adaptive adjustment, comprises the following steps:
[0034] S1: Using automatic exposure to collect iris images of human eyes;
[0035] S2: Analyze the collected image, and obtain the position information of the iris in the image;
[0036] S3: According to the position information of the human eye, adjust the exposure brightness statistics area or modify the ex...
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The invention discloses a method for adaptively adjusting exposure and contrast of a human eye iris image. The method comprises the following steps of: acquiring the human eye iris image by using automatic exposure; analyzing the acquired image; adjusting an exposure brightness statistical region or modifying an exposure statistical weight according to the human eye position information, and adjusting exposure time; counting the number of pixel points of all pixel values of a human eye area in the acquired image; extracting the median of the pixel value occupied by the iris in the eyeball areaby using the curve characteristics of the obtained smooth histogram; finely adjusting the exposure time until the iris average brightness value falls into an image standard specified value range; extracting histogram information of the image at the moment. The contrast between the pupil and the iris and the contrast between the sclera and the iris are improved. According to the invention, the exposure time and the contrast ratio are automatically adjusted, and the unification of a fixed exposure use scene and the deviation of the fixed contrast ratio on different human eye iris images are avoided.
Description
technical field [0001] The invention relates to the technical field of digital image processing and image acquisition, in particular to a method for adaptively adjusting the exposure and contrast of a human iris image. Background technique [0002] The iris is the ring-shaped textured area outside the pupil in the human eyeball. It is widely used in security systems as one of the biometric features for identification. In practical applications, before iris recognition, it is necessary to use a camera to collect images of the iris under near-infrared light. For iris images, my country has relatively strict industry standards, which need to comply with the "Security Iris Recognition Application Image Technical Requirements". Cameras with different specifications have different parameters for capturing images, and the images need to be adjusted, including exposure time, white balance, focus, and contrast. Among them, the exposure time can be adjusted within a limited range t...
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Login to View More IPC IPC(8): G06T5/00G06T5/40
CPCG06T5/40G06T2207/30041G06T5/94
Inventor 陶茜孙敬牛同斌
Owner FOCTEK PHOTONICS LNC