Mathematics Essay 代写:指纹图像增强

Keywords:Mathematics Essay 代写

指纹图像增强，旨在减少噪音，提高脊和山谷之间的对比度指纹图像，特别是在灰度指纹图像（王玮等，2008）。指纹图像增强，可以进行任何二进制脊图像或灰度图像（S. Greenberg等人，2002）。大多数情况下，指纹图像增强算法接收输入指纹图像，在输入图像上施加一组中间步骤，并最终输出增强图像（林红等人，1998）。由于指纹图像增强的目的是提高输入的指纹图像的脊形结构便于脊和特征提取的清晰，指纹增强算法应该不会导致任何虚假的脊线结构。 指纹增强语境过滤器被欧达梦与尼克森介绍（1989）每个滤波器具有各向异性平滑核的长轴方向平行于相应的方向。通过这种方法，在垂直于屋脊方向对比度可以增加表演时的平滑也在垄的方向。 Sherlock等人的研究成果。（1994）提出了一种基于方向傅立叶滤波的指纹增强方法。在所提出的方法中，原始图像过滤由预先计算的方向滤波器在频域。然后，根据在原始图像的同一位置上的像素的方向从预滤波的图像中合并像素值来重建增强图像。该方法已成功地减少了伪特征点的数量也减少了处理时间，也增加了总人数的候选检测。但也有一些弱点的方法，方法只能读取格网间距如16由16个像素，也会有点细节还原过程后失踪的检测。 从过去的研究，香港等。（1998）提出了一种从一组滤波后的图像采用Gabor滤波器对输入的指纹图像的方向场分解方法得到的估计。从这个方法中，香港已成功提高清晰的山脊线和山谷基于拟合指数和验证性能，还能够识别不可恢复的区域结构。但研究的不足之处在于使用的方法不能读取图像的正弦波脊和谷。

Mathematics Essay 代写:指纹图像增强

Fingerprint image enhancement intended to reduced noises and improve the contrast between ridge and valley in the fingerprint images which specifically in gray-level fingerprint images (Wei Wang et al., 2008). Fingerprint image enhancement can be conducted on either binary ridge images or gray-scale images (S. Greenberg et al., 2002). Mostly, a fingerprint image enhancement algorithm receives an input fingerprint image, applies a set of intermediate steps on the input image and finally outputs the enhanced image (Lin Hong et al., 1998). Since the objective of a fingerprint image enhancement is to improve the clarity of ridge structures of input fingerprint images to facilitate the extraction of ridges and minutiae, a fingerprint enhancement algorithm should not result in any spurious ridge structures.The contextual filters in fingerprint enhancement was introduced by O’Gorman and Nickerson (1989) which each filter has an anisotropic smoothing kernel whose major axis is oriented parallel to corresponding direction. By this method, contrast in the direction perpendicular to the ridge can be increase while performing smoothening also in the direction of ridge.A research results by Sherlock et al. (1994), presented a fingerprint enhancement based on directional Fourier Filtering. In the method presented, the original image is filtered by pre-computed directional filter in frequency domain. Then, the enhanced image is reconstructed by combining the pixel values from the pre-filtered images according to the direction of the pixel at the same position in the original image. This method has successfully reduce the number of false minutiae and also reducing processing time and also increased the total number candidate detected. But there are some weakness detected in the presented method which are the method can only read square grid spaced such as 16 by 16 pixel and also there will be minutiae missing after the process of minutiae reduction.From the past studies, Hong et al. (1998) has proposed a decomposition method to estimate the orientation field from a set of filtered images obtained by applying a bank of Gabor Filters on the input fingerprint images. From this proposed method, Hong has successfully improve the clarity of ridge and valley structure based on goodness index and the verification performance and also able to identify unrecoverable regions. But the weakness of the research are the methods use cannot read image with Sinusoidal-shaped waves of ridges and valleys.