zoukankan      html  css  js  c++  java
  • python库skimage 应用canny边缘探测算法

    Canny算法

    请参考:Canny算法python手动实现
    请参考:Canny边缘检测算法原理及opencv实现

    skimage库中函数

    skimage.feature.canny(image, sigma=1.0, low_threshold=None, high_threshold=None, mask=None, use_quantiles=False)
    sigma:高斯滤波器的标准差
    low_threshold:Canny算法最后一步中,小于该阈值的像素直接置为0
    high_threshold:Canny算法最后一步中,大于该阈值的像素直接置为255

    实验:Canny算法作用于图像

    """
    ===================
    Canny edge detector
    ===================
    
    The Canny filter is a multi-stage edge detector. It uses a filter based on the
    derivative of a Gaussian in order to compute the intensity of the gradients.The
    Gaussian reduces the effect of noise present in the image. Then, potential
    edges are thinned down to 1-pixel curves by removing non-maximum pixels of the
    gradient magnitude. Finally, edge pixels are kept or removed using hysteresis
    thresholding on the gradient magnitude.
    
    The Canny has three adjustable parameters: the width of the Gaussian (the
    noisier the image, the greater the width), and the low and high threshold for
    the hysteresis thresholding.
    
    """
    import numpy as np
    import matplotlib.pyplot as plt
    from scipy import ndimage as ndi
    
    from skimage import feature
    
    
    # Generate noisy image of a square
    im = np.zeros((128, 128))
    im[32:-32, 32:-32] = 1
    
    im = ndi.rotate(im, 15, mode='constant')
    im = ndi.gaussian_filter(im, 4)
    im += 0.2 * np.random.random(im.shape)
    
    # Compute the Canny filter for two values of sigma
    edges1 = feature.canny(im)
    edges2 = feature.canny(im, sigma=3)
    
    # display results
    fig, (ax1, ax2, ax3) = plt.subplots(nrows=1, ncols=3, figsize=(8, 3),
                                        sharex=True, sharey=True)
    
    ax1.imshow(im, cmap=plt.cm.gray)
    ax1.axis('off')
    ax1.set_title('noisy image', fontsize=20)
    
    ax2.imshow(edges1, cmap=plt.cm.gray)
    ax2.axis('off')
    ax2.set_title(r'Canny filter, $sigma=1$', fontsize=20)
    
    ax3.imshow(edges2, cmap=plt.cm.gray)
    ax3.axis('off')
    ax3.set_title(r'Canny filter, $sigma=3$', fontsize=20)
    
    fig.tight_layout()
    
    plt.show()
    

    实验结果

  • 相关阅读:
    hdu 2647 (拓扑)
    iOS 陀螺仪
    GetMessage()函数使用时的注意
    Button按钮释放时的事件
    深入理解递归:全排列问题
    json实现jsp分页
    EJB事务管理bug修改记
    hdu1159Common Subsequence
    HDOJ 4512 吉哥系列故事——完美队形I
    随机生成长度为100的数组,数组元素为1到10,统计出现次数最多和最少的元素
  • 原文地址:https://www.cnblogs.com/wojianxin/p/12655416.html
Copyright © 2011-2022 走看看