Image processing OpenCV的脉冲、高斯和椒盐噪声
我正在研究著名的图像处理和谈论图像恢复,很多例子都是用计算机产生的噪声(高斯、椒盐等)来完成的。在MATLAB中,有一些内置函数可以实现这一点。OpenCV呢?据我所知,没有像Matlab那样方便的内置函数。但只需几行代码,您就可以自己创建这些图像 例如,加性高斯噪声:Image processing OpenCV的脉冲、高斯和椒盐噪声,image-processing,opencv,Image Processing,Opencv,我正在研究著名的图像处理和谈论图像恢复,很多例子都是用计算机产生的噪声(高斯、椒盐等)来完成的。在MATLAB中,有一些内置函数可以实现这一点。OpenCV呢?据我所知,没有像Matlab那样方便的内置函数。但只需几行代码,您就可以自己创建这些图像 例如,加性高斯噪声: Mat gaussian_noise = img.clone(); randn(gaussian_noise,128,30); 椒盐噪音: Mat saltpepper_noise = Mat::zeros(img.rows,
Mat gaussian_noise = img.clone();
randn(gaussian_noise,128,30);
椒盐噪音:
Mat saltpepper_noise = Mat::zeros(img.rows, img.cols,CV_8U);
randu(saltpepper_noise,0,255);
Mat black = saltpepper_noise < 30;
Mat white = saltpepper_noise > 225;
Mat saltpepper_img = img.clone();
saltpepper_img.setTo(255,white);
saltpepper_img.setTo(0,black);
Mat saltpepper\u noise=Mat::零(img.rows、img.cols、CV\u 8U);
randu(Saltu噪音,0255);
Mat black=盐雾噪声<30;
Mat white=盐胡椒噪声>225;
Mat saltpepper_img=img.clone();
盐胡椒粉(255,白色);
盐胡椒(0,黑色);
#添加噪音
[m,n]=img.shape
saltpepper_噪声=零((m,n));
噪声=兰特(m,n)#创建从0到1的统一随机变量
对于范围(0,m)内的i:
对于范围(0,n)内的j:
如果噪声[i,j]
向图像添加高斯、椒盐斑点和泊松噪声的简单函数
可以使用NumPy矩阵运算以非常简单的方式添加“Salt&Pepper”噪声
def add_salt_and_pepper(gb, prob):
'''Adds "Salt & Pepper" noise to an image.
gb: should be one-channel image with pixels in [0, 1] range
prob: probability (threshold) that controls level of noise'''
rnd = np.random.rand(gb.shape[0], gb.shape[1])
noisy = gb.copy()
noisy[rnd < prob] = 0
noisy[rnd > 1 - prob] = 1
return noisy
def添加盐和胡椒粉(gb,prob):
''向图像添加“椒盐”噪声。
gb:应为单通道图像,像素在[0,1]范围内
问题:控制噪音级别“”的概率(阈值)
rnd=np.random.rand(gb.shape[0],gb.shape[1])
noised=gb.copy()
噪声[rnd1-概率]=1
回音嘈杂
均值和西格玛的值可以改变,以引起噪声的特定变化,如高斯噪声或椒盐噪声等。
您可以根据需要使用randn或randu。请查看文档:
虽然没有像matlab中那样的内置函数
“imnoise(图像、noiseType、NoiseLevel)”但我们可以轻松地随机添加所需数量
手动将有值脉冲噪声或椒盐输入图像。
1.添加随机值脉冲噪声
将随机导入为r
def addRvinGray(图像,n):#在灰度中添加随机值脉冲噪声
''参数:
image:type=numpy数组。要在其中添加噪波的输入图像。
n:噪声级(百分比)“”
k=0#计数器变量
ih=图像.形状[0]
iw=image.shape[1]
noisepixels=(ih*iw*n)/100#这里我们计算要改变的像素数。
对于范围内的i(ih*iw):
如果k有来自scikit映像包的功能。它有几种内置的噪声模式,例如gaussian
,s&p
(用于椒盐噪声),possion
和spoke
下面我展示了一个如何使用此方法的示例
from PIL import Image
import numpy as np
from skimage.util import random_noise
im = Image.open("test.jpg")
# convert PIL Image to ndarray
im_arr = np.asarray(im)
# random_noise() method will convert image in [0, 255] to [0, 1.0],
# inherently it use np.random.normal() to create normal distribution
# and adds the generated noised back to image
noise_img = random_noise(im_arr, mode='gaussian', var=0.05**2)
noise_img = (255*noise_img).astype(np.uint8)
img = Image.fromarray(noise_img)
img.show()
还有一个名为的包,专门用于以各种方式增强图像。它提供高斯、泊松和椒盐噪声增强。以下是如何使用它向图像添加噪波:
from PIL import Image
import numpy as np
from imgaug import augmenters as iaa
def main():
im = Image.open("bg_img.jpg")
im_arr = np.asarray(im)
# gaussian noise
# aug = iaa.AdditiveGaussianNoise(loc=0, scale=0.1*255)
# poisson noise
# aug = iaa.AdditivePoissonNoise(lam=10.0, per_channel=True)
# salt and pepper noise
aug = iaa.SaltAndPepper(p=0.05)
im_arr = aug.augment_image(im_arr)
im = Image.fromarray(im_arr).convert('RGB')
im.show()
if __name__ == "__main__":
main()
我对@Shubham Pachori的代码做了一些修改。将图像读取到numpy阵列中时,默认的数据类型为uint8,在图像上添加噪波时会导致换行
import numpy as np
from PIL import Image
"""
image: read through PIL.Image.open('path')
sigma: variance of gaussian noise
factor: the bigger this value is, the more noisy is the poisson_noised image
##IMPORTANT: when reading a image into numpy arrary, the default dtype is uint8,
which can cause wrapping when adding noise onto the image.
E.g, example = np.array([128,240,255], dtype='uint8')
example + 50 = np.array([178,44,49], dtype='uint8')
Transfer np.array to dtype='int16' can solve this problem.
"""
def gaussian_noise(image, sigma):
img = np.array(image)
noise = np.random.randn(img.shape[0], img.shape[1], img.shape[2])
img = img.astype('int16')
img_noise = img + noise * sigma
img_noise = np.clip(img_noise, 0, 255)
img_noise = img_noise.astype('uint8')
return Image.fromarray(img_noise)
def poisson_noise(image, factor):
factor = 1 / factor
img = np.array(image)
img = img.astype('int16')
img_noise = np.random.poisson(img * factor) / float(factor)
np.clip(img_noise, 0, 255, img_noise)
img_noise = img_noise.astype('uint8')
return Image.fromarray(img_noise)
所以这个问题不是关于MATLAB的…?不,你是对的,我删除了标记MATLAB当我使用高斯类型时,我的图像变成全白色。我是这样做的:image=cv2.imread(fn)noise\u gauss=noise(“高斯”,image)cv2.imshow(“高斯”,noise\u gauss)。似乎产生的噪音不是同一类型的,加起来会引起一些奇怪的问题transformation@Lxu你能展示这个转换是什么样子吗?@Lxu我相信这是因为numpy数组类型变成了float64
。在你把它传递给cv2.imshow之前,只需写下noise\u gauss=noise\u gauss.astype('uint8')
,实际上把大部分问题放在一个URL中(可能会消失)是不好的风格,所以请不要在回答问题时重复这一点!尝试在输入框中编写基本解决方案,并使用代码格式化来格式化代码。您的代码确实可以完成这项工作,但只能在一个通道中完成。您需要mean/sigma是一组值,比如:sigma=(10,10,10)
import random as r
def addRvinGray(image,n): # add random valued impulse noise in grayscale
'''parameters:
image: type=numpy array. input image in which you want add noise.
n: noise level (in percentage)'''
k=0 # counter variable
ih=image.shape[0]
iw=image.shape[1]
noisypixels=(ih*iw*n)/100 # here we calculate the number of pixels to be altered.
for i in range(ih*iw):
if k<noisypixels:
image[r.randrange(0,ih)][r.randrange(0,iw)]=r.randrange(0,256) #access random pixel in the image gives random intensity (0-255)
k+=1
else:
break
return image
def addSaltGray(image,n): #add salt-&-pepper noise in grayscale image
k=0
salt=True
ih=image.shape[0]
iw=image.shape[1]
noisypixels=(ih*iw*n)/100
for i in range(ih*iw):
if k<noisypixels: #keep track of noise level
if salt==True:
image[r.randrange(0,ih)][r.randrange(0,iw)]=255
salt=False
else:
image[r.randrange(0,ih)][r.randrange(0,iw)]=0
salt=True
k+=1
else:
break
return image
from PIL import Image
import numpy as np
from skimage.util import random_noise
im = Image.open("test.jpg")
# convert PIL Image to ndarray
im_arr = np.asarray(im)
# random_noise() method will convert image in [0, 255] to [0, 1.0],
# inherently it use np.random.normal() to create normal distribution
# and adds the generated noised back to image
noise_img = random_noise(im_arr, mode='gaussian', var=0.05**2)
noise_img = (255*noise_img).astype(np.uint8)
img = Image.fromarray(noise_img)
img.show()
from PIL import Image
import numpy as np
from imgaug import augmenters as iaa
def main():
im = Image.open("bg_img.jpg")
im_arr = np.asarray(im)
# gaussian noise
# aug = iaa.AdditiveGaussianNoise(loc=0, scale=0.1*255)
# poisson noise
# aug = iaa.AdditivePoissonNoise(lam=10.0, per_channel=True)
# salt and pepper noise
aug = iaa.SaltAndPepper(p=0.05)
im_arr = aug.augment_image(im_arr)
im = Image.fromarray(im_arr).convert('RGB')
im.show()
if __name__ == "__main__":
main()
skimage.util.random_noise(image, mode='gaussian', seed=None, clip=True, **kwargs)
import numpy as np
from PIL import Image
"""
image: read through PIL.Image.open('path')
sigma: variance of gaussian noise
factor: the bigger this value is, the more noisy is the poisson_noised image
##IMPORTANT: when reading a image into numpy arrary, the default dtype is uint8,
which can cause wrapping when adding noise onto the image.
E.g, example = np.array([128,240,255], dtype='uint8')
example + 50 = np.array([178,44,49], dtype='uint8')
Transfer np.array to dtype='int16' can solve this problem.
"""
def gaussian_noise(image, sigma):
img = np.array(image)
noise = np.random.randn(img.shape[0], img.shape[1], img.shape[2])
img = img.astype('int16')
img_noise = img + noise * sigma
img_noise = np.clip(img_noise, 0, 255)
img_noise = img_noise.astype('uint8')
return Image.fromarray(img_noise)
def poisson_noise(image, factor):
factor = 1 / factor
img = np.array(image)
img = img.astype('int16')
img_noise = np.random.poisson(img * factor) / float(factor)
np.clip(img_noise, 0, 255, img_noise)
img_noise = img_noise.astype('uint8')
return Image.fromarray(img_noise)