Salt and pepper code in matlab

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Rooter Boy
Rooter Boy 2020-11-10
评论： Image Analyst 2020-11-10
I want to convert from this opencv code to matlab code.
My tried code:
% I generated random salt & pepper noise
dim = size(I);
[m, n] = size(I);
saltpepper_noise=zeros((m, n));
saltpepper_noise=rand(m,n); #creates a uniform random variable from 0 to 1
for i in range(0,m):
for j in range(0,n):
if saltpepper_noise[i,j]<=0.5:
saltpepper_noise[i,j]=0
else:
saltpepper_noise[i,j]=255
  1 个评论
Nathan Bblanc
Nathan Bblanc 2020-11-10
Not sure I understand your code fully, is I defined before the code begins?
in any case, a few corrections
  • the asignment [m,n]=x is impossible in matlab, you can should define them seperatly:
m=size(I)(1)
n=size(I)(2)
  • no need to define saltpepper_noise twice, you can just use the second line
  • in a for loop, you use the syntax for i=1:m
in general, i suggest you use matlab's online documentation, it's very helpful and full of examples

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回答（2 个）

Image Analyst
Image Analyst 2020-11-10
编辑：Image Analyst 2020-11-10
If you want to use conditionals and be as close as possible to that code (instead of using the built-in imnoise function), then you can do this:
% Get grayscale image
saltpepper_img = imread('cameraman.tif');
[img.rows, img.cols] = size(saltpepper_img);
% Create noise image.
saltpepper_noise = randi(255, img.rows, img.cols, 'uint8');
subplot(2, 2, 1);
imshow(saltpepper_noise);
title('Original Noise', 'FontSize', 15);
black = saltpepper_noise < 10;
subplot(2, 2, 2);
imshow(black);
title('Black Locations', 'FontSize', 15);
white = saltpepper_noise > 245;
subplot(2, 2, 3);
imshow(white);
title('White Locations', 'FontSize', 15);
% Assign black and white to gray scale image.
saltpepper_img(black) = 0;
saltpepper_img(white) = 255;
subplot(2, 2, 4);
imshow(saltpepper_img);
title('Grayscale image with noise', 'FontSize', 15);
Also see attached demos.
  2 个评论
Image Analyst
Image Analyst 2020-11-10
In this forum, you can thank people by clicking the Vote icon or "Accepting the answer" to give them reputation points. Thanks in advance.

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Image Analyst
Image Analyst 2020-11-10
There is a salt and pepper option for imnoise(). Just use that.
  1 个评论
Rooter Boy
Rooter Boy 2020-11-10
I want to use with if conditionals.
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);
I don't know how to adapt this for my codes.

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