Image processing: Convolution & Correlation

Question

Jiby 2022-10-13

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1824263-image-processing-convolution-correlation

回答： V Sairam Reddy 2022-10-18

在 MATLAB Online 中打开

a. What are the pixel dimensions of ct.jpg?

b. What would the pixel dimensions of ct.jpg be after correlation or convolution with itself?

Can i know whether i am doing it right

Pixel dimensions of ct.jpg

%First set colormap and and load image 
clf reset 
% colormap('gray')
ct=imread('ct.jpeg')
%Pixels of the image is identified using size function
[rows, columns] = size(ct)
whos ct %verify number of pixels in the image 
%Answer(a) Pixel dimensions of the image is [252*302]

%Convolution of image with itself
subplot(2,2,1), imagesc(ct); 
title('Raw Image'), xlabel i, ylabel j, colorbar 
subplot(2,2,2), imagesc(conv2(ct,ct)); 
title('Convolution Result'), xlabel i, ylabel j, colorbar  
ConPixel = conv2(ct,ct)
[rowsofconv, columsofconv] = size(ConPixel)
imwrite(ConPixel,'ConPixel1.jpg','jpg')
subplot(2,2,3), imagesc(ConPixel);
title('Saved Convolution Result'), xlabel i, ylabel j, colorbar  
%Answer(b) Pixel dimensions of the Convol image is [503*603]

%Correlation of image with itself
close all hidden
% colormap('gray')
subplot(2,2,1), imagesc(ct); 
title('Raw Image'), xlabel i, ylabel j, colorbar 
subplot(2,2,2), imagesc(xcorr2(ct,ct)); 
title('Correlation Result'), xlabel i, ylabel j, colorbar  
CorPixel = xcorr2(ct,ct)
[rowsofcorr, columsofcorr] = size(CorPixel)
imwrite(CorPixel,'CorrPixel1.jpg','jpg')
subplot(2,2,3), imagesc(CorPixel);
title('Saved Correlation Result'), xlabel i, ylabel j, colorbar
%Answer(b) Pixel dimensions of the Correl image is [503*603]

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Answer 1

V Sairam Reddy 2022-10-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1824263-image-processing-convolution-correlation#answer_1077828

在 MATLAB Online 中打开

Yes, you are right.

To find the pixel dimensions of "ct.jpeg" you can read it and use "size()" command.

% Read the Image.
ct_image = imread('ct.jpeg');
% Find pixel dimensions of Image.
[no_of_rows, no_of_columns] = size(ct_image);

you can find the pixel dimensions of the image after convolution or correlation with itself the same way.

% Find pixel dimensions of Image convoluted with Itself.
[no_of_rows_in_Conv_Image, no_of_columns_in_Conv_Image] = size(conv2(ct_image,ct_image));
% Find pixel dimensions of Image Correlated with Itself.
[no_of_rows_in_Corr_Image, no_of_columns_in_Corr_Image] = size(xcorr2(ct_image,ct_image));