How can I convert grayscale image to a binary image without using a toolbox function?
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I want to create a binary image from a gray scale image, using a specific threshold value of 0.2, but without using im2bw(), which is in the Image Processing Toolbox. How do I do it?
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Accepted Answer
Image Analyst
on 14 Oct 2016
Just threshold:
binaryImage = grayImage > 0.2; % or < or <= or >= (whatever you want).
No toolbox needed.
11 Comments
Image Analyst
on 24 Aug 2023
Don't use gray as the name of your variable. It is the name of a built-in function. What do you mean by "back"? What happened to it. You still have (the badly named) "gray" in your functions workspace, right? So just use it. You didn't say "clear gray" did you? So it should still be there.
DGM
on 24 Aug 2023
To be clear, let's assume an empty workspace:
inpict = imread('cameraman.tif'); % a uint8-class grayscale image
mask = inpict >= 128; % a logical-class binary image
At this point there are two variables in the workspace: inpict and mask. You can't back-calculate inpict from mask, but you don't have to, since it's still in memory. Just use inpict.
More Answers (1)
Ali nafaa
on 29 Nov 2022
Edited: DGM
on 24 Aug 2023
x = imread('cameraman.tif');
figure,imshow(x);
[r,c] = size (x);
output=zeros(r,c);
for i = 1 : r
for j = 1 : c
if x(i,j) > 128
output(i,j)=1;
else
output(i,j)=0;
end
end
end
figure,imshow(output);
1 Comment
DGM
on 24 Aug 2023
There's no need for the loops. The appropriate answer was given years prior.
inpict = imread('cameraman.tif'); % a uint8-class grayscale image
mask = inpict >= 128; % a logical-class binary image
... or if inpict is not needed for anything, you can avoid the intermediate result:
mask = imread('cameraman.tif') >= 128; % a logical-class binary image
Display them however you choose.
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