CODEWITHSUNDEEP
matlabimage-processing
user9145305
user9145305

Reputation:

Convolving an image with a mask displays an all white image

Very new to MatLab, just figuring some things out and had a question. I am basically trying to filter/blur an image using conv2() but I am getting an all white image when I am using imshow()

I am reading the image in with

testImage = imread('test.bmp');

This is a uint8 image of a grayscale.

I am trying to convolve the image with a 4 x 4 matrix.

fourByFour = ones(4);

When I actually execute, I am getting all white with imshow()

convolvedImage = conv2(testImage, fourByFour);

I should expect a filter placed on the image, not an entirely white one. Any help would be appreciated.

Upvotes: 1

Views: 855

Answers (2)

user10795198
user10795198

Reputation: 1

test = imread('test.bmp');
% read test image that is  .bmp format and size :294x294x3 and uint8.

fourByFour = ones(4); 
% define 4 * 4 matrix all ones
test=rgb2gray(test);
% convert colorimage into gray
convolvedImage = conv2(double(test), double(fourByFour));
%perform the convolution
figure, imshow(convolvedImage,[])
% display the image

Upvotes: -1

Somaye
Somaye

Reputation: 114

I don't have your test image so I explain on an image. As the definition of conv2 it returns the two-dimensional convolution. So please look at this little code:

clc;% clear the screen
clear all;% clear everything
close all;% close all figures

test = imread('test.bmp');
% read test image that is  .bmp format and size :294x294x3 and uint8.

fourByFour = ones(4); % define 4 * 4 matrix all ones

convolvedImage = conv2(test(:,:,1), fourByFour);
%apply the ones matrix on image but to use conv2 on this image we apply on one of channels

figure, imshow(convolvedImage,[])

This is my command window, out put: enter image description here

I'm using MAtlab 2017a, and if I use conv2(test, fourByFour); instead of conv2(test(:,:,1), fourByFour); ,the error is :

Error using conv2
N-D arrays are not supported.

So we should attention to class type and dimensions. And one more thing, in your command window please type edit conv2 you can read the details of this function and how to use it, but never edit it:). Thanks

Upvotes: 1

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