# Unsteady State Lightweight Iris Certification Based on Multi-Algorithm Parallel Integration
## 3 Lightweight Unsteady State Constrained Iris Certification  
The overall process of the algorithm is shown in Figure 6.  
**Image processing layer. ** Biometric information focuses on the uniqueness and stability of features, such as the shape and size of facial features in face recognition [30]. The variation of the amount of information in each part of the iris can be used as a unique iris feature [31], because the relative change relationship among the iris key points rarely changes greatly, regardless of the change of the external environment and the acquisition status. Therefore, the stability of the features means that the information measured or obtained is robust to certain distortions. Figure 4: Steady change of constrained iris texture taken of the same person. Figure 5: Unsteady change of constrained iris texture taken by the same person: (**a**) normal; (**b**) normal illumination clear and undeflected; (**c**) normal illumination blur and deflected; (**d**) dark illumination clear and undeflected. Figure 3: Examples of eye images of the same person at different shooting times: (**a,b**) clear grayscale image with normal light conditions; (**c,d**) clear grayscale image with darker and brighter light conditions, respectively; (**e,f**) blurred grayscale images. Based on these two points, in this algorithm, the stable texture after the iris is subjected to multiple filtering processing is set as an effective feature, which is specifically defined as: feature points existing on each of the filtered processed images in the multi-filter processing. Only the image inside the iris texture can easily be preserved in the image after the edge is highlighted or the image smoothing is processed, from which it is possible to effectively retain enough of the internal feature points of the iris texture reflecting the amount of iris information. There are two reasons for filtering images: on the one hand, the image is smoothed and iris noise is removed, thereby reducing unnecessary interference; on the other hand, textures will be highlighted, and iris edge information can be saved. To ensure that the points in the iris texture can be fully expressed, in this paper, six filters that can achieve these two purposes are selected in the image processing layer, including: Gaussian filter, Square filter, Median filter, Bilateral filter, Equalization histogram and Laplacian of Gaussian. Gaussian filter: A linear smoothing filter that performs a weighted average. The value of each pixel is obtained by weighted averaging of its own and other pixel values in the neighborhood. Square filter: A linear filtering technique where each output pixel is the average of pixel values in the kernel neighborhood. Median filter: A non-linear smoothing technique that sets the grayscale value of each pixel to the median value of all pixels within a neighborhood window at that point. Bilateral filter: A non-linear filtering method that combines the spatial proximity of image with the similarity of pixel values. It also considers the spatial information and the gray similarity to achieve the purpose of edge preservation and denoising. Equalization histogram: The nonlinear stretch is performed on the image, the image pixel values can be reassigned and the number of pixels in a certain grayscale range is approximately the same, which can increase the grayscale dynamic range of image. Laplacian of Gaussian: optimal smoothing is performed on the original image which can suppress noise. These six kinds of filters are combined to ensure that the feature points inside the iris texture are preserved, so that the information variation law can still be effectively expressed, and the unstable noise points are removed to ensure the validity of the stable features. The features are then made to conform to the definitions in this paper. **Feature recognition layer:** Gabor and Haar are the most commonly used iris feature extraction filters. Their performance has been fully tested, and they have certain iris rotation invariance.