使用Python-OpenCV向图片添加噪声的实现(高斯噪声、椒盐噪声)


						在matlab中，存在执行直接得函数来添加高斯噪声和椒盐噪声。Python-OpenCV中虽然不存在直接得函数，但是很容易使用相关的函数来实现。

代码：





import numpy as np

import random

import cv2



def sp_noise(image,prob):

  '''

  添加椒盐噪声

  prob:噪声比例 

  '''

  output = np.zeros(image.shape,np.uint8)

  thres = 1 - prob 

  for i in range(image.shape[0]):

    for j in range(image.shape[1]):

      rdn = random.random()

      if rdn < prob:

        output[i][j] = 0

      elif rdn > thres:

        output[i][j] = 255

      else:

        output[i][j] = image[i][j]

  return output





def gasuss_noise(image, mean=0, var=0.001):

  ''' 

    添加高斯噪声

    mean : 均值 

    var : 方差

  '''

  image = np.array(image/255, dtype=float)

  noise = np.random.normal(mean, var ** 0.5, image.shape)

  out = image + noise

  if out.min() < 0:

    low_clip = -1.

  else:

    low_clip = 0.

  out = np.clip(out, low_clip, 1.0)

  out = np.uint8(out*255)

  #cv.imshow("gasuss", out)

  return out







可见，只要我们得到满足某个分布的多维数组，就能作为噪声添加到图片中。

例如：





import cv2

import numpy as np



>>> im = np.empty((5,5), np.uint8) # needs preallocated input image

>>> im

array([[248, 168, 58,  2,  1], # uninitialized memory counts as random, too ? fun ;) 

    [ 0, 100,  2,  0, 101],

    [ 0,  0, 106,  2,  0],

    [131,  2,  0, 90,  3],

    [ 0, 100,  1,  0, 83]], dtype=uint8)

>>> im = np.zeros((5,5), np.uint8) # seriously now.

>>> im

array([[0, 0, 0, 0, 0],

    [0, 0, 0, 0, 0],

    [0, 0, 0, 0, 0],

    [0, 0, 0, 0, 0],

    [0, 0, 0, 0, 0]], dtype=uint8)

>>> cv2.randn(im,(0),(99))     # normal

array([[ 0, 76,  0, 129,  0],

    [ 0,  0,  0, 188, 27],

    [ 0, 152,  0,  0,  0],

    [ 0,  0, 134, 79,  0],

    [ 0, 181, 36, 128,  0]], dtype=uint8)

>>> cv2.randu(im,(0),(99))     # uniform

array([[19, 53, 2, 86, 82],

    [86, 73, 40, 64, 78],

    [34, 20, 62, 80, 7],

    [24, 92, 37, 60, 72],

    [40, 12, 27, 33, 18]], dtype=uint8)







然后再：





img = ...

noise = ...



image = img + noise





参考链接：

1、http://stackoverflow.com/questions/22937589/how-to-add-noise-gaussian-salt-and-pepper-etc-to-image-in-python-with-opencv#

2、http://stackoverflow.com/questions/14435632/impulse-gaussian-and-salt-and-pepper-noise-with-opencv#



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