Out-of-focus iris image restoration method based on frequency domain parameter estimation

A technology of iris image and focused iris, which is applied in image enhancement, image analysis, image data processing, etc., can solve the problem of not being able to obtain clear and accurately focused iris images, achieve accurate restoration results, improve iris positioning accuracy and recognition performance, Corrected the effect of changes in PSF

Inactive Publication Date: 2014-08-06
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

Commonly used iris recognition systems collect high-quality iris images with the cooperation of the subject. However, in actual image acquisition, due to the limitation of t

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  • Out-of-focus iris image restoration method based on frequency domain parameter estimation
  • Out-of-focus iris image restoration method based on frequency domain parameter estimation
  • Out-of-focus iris image restoration method based on frequency domain parameter estimation

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[0036] Hereinafter, various details involved in the technical solution of the present invention will be described in detail with reference to the embodiments and the drawings.

[0037] Due to the non-cooperative mode of the person being collected or the environmental influences such as the illumination during the collection process, the defocused and blurred iris image is caused by the previous method. The quality evaluation is performed first, and this type of image is eliminated and not used for identification. Since such images contain available iris information, the restoration of these blurred iris images can enhance the ease of use of the recognition system.

[0038] The defocused iris image restoration method proposed by the present invention can be used in a variety of iris image recognition systems. The flowchart is as follows figure 1 As shown, including the following steps:

[0039] S1. Perform Fourier transform on the defocused iris image to obtain the corresponding frequ...

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Abstract

The invention discloses an out-of-focus iris image restoration method based on frequency domain parameter estimation. The method comprises the steps that Fourier transform is carried out on an out-of-focus fuzzy iris image to obtain a frequency domain image at first; then Hough transform is adopted for carrying out parameter calculation on a first dark ring in the frequency domain image in an elliptic curve mode, the out-of-focus radius is calculated through the parameters, a point spread function is initialized, a blind deconvolution iteration method is adopted for estimating Fourier transform of a clear image, and a clear iris image is obtained through Fourier transform. According to the out-of-focus iris image restoration method based on frequency domain parameter estimation, out-of-focus parameters can be effectively estimated on the condition that optical system parameters are not known, fuzzy iris image restoration is achieved, the influence of the out-of-focus iris image on iris recognition performance is effectively reduced, the system robustness is improved, the restriction on users is loosened, and the application field of an iris reorganization system is broadened.

Description

technical field [0001] The invention belongs to the field of biological feature recognition, and relates to technologies such as digital image processing, statistical learning, and pattern recognition, and in particular to a method for calculating the defocus radius in the frequency domain and performing image restoration on a defocused iris image obtained by an unknown parameter system. Background technique [0002] Iris-based identification plays an important role in biometric identification technology due to its high reliability, stability and non-invasiveness. Commonly used iris recognition systems collect high-quality iris images with the cooperation of the subject. However, in actual image acquisition, due to the limitation of the depth of field of the optical system, it is impossible to obtain clear and accurate images in some non-cooperative modes or long-distance recognition. In-focus iris image. Defocused blurred iris images are often discarded in the image qualit...

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Application Information

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IPC IPC(8): G06T5/00G06T7/00
Inventor 何玉青任慧颖王思远黄坤侯博严
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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