Replace values to create an image with binary values (0,1)

2022 2 21
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更新时间：2022 2 21
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Dear Researchers,
I have a matrix (2D image) which I need to replace values in such a way to obtain binary image.
I used Max function which replace values for one condition. However, In this case, I need to replace values greater and less than zero with zero (0) and replace all values = zero with 1.
I have uploaded image, vaues are ranging from (-3.8 to 3.8), can you please guide me on how to obtain binary image.
Many thanks in advance.

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Image Analyst
Image Analyst 2022-2-21

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OK, now that you've added the .mat file, there are no values that are exactly 0. You need to define a range.
s = load('image.mat')
V = s.V;
subplot(2, 2, 1);
imshow(V, []);
colorbar
subplot(2, 2, 3:4);
histogram(V, 256);
grid on;
title('Histogram of V')
xlabel('Value')
ylabel('Count')
% There are no values that are exactly zero so let's pick a tolerance
tolerance = 0.1;
binaryImage = abs(V) < tolerance;
subplot(2, 2, 2);
imshow(binaryImage, []);

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Amjad Iqbal
Amjad Iqbal 2022-2-21
Perfect, It works, with what i required, now it's all about siffting and get more accurate results.
Many thanks dear @Image Analys

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更多回答（2 个）

Cris LaPierre
Cris LaPierre 2022-2-21
Ran in:

0 个投票

Ran in:
Sounds like a logical result would work.
a = [-3.8 -1 0 1 3.8];
c = a~=1
c = 1×5 logical array
1 1 1 0 1

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Amjad Iqbal
Amjad Iqbal 2022-2-21
Dear @Cris LaPierre
Thanks for propmt reply, since this replace values accroding to the condition, but give a logical matrix, thus I need to obtain binary image which I can't obtain by logical matrix.
Arthur Reis
Arthur Reis 2022-2-21
You can then convert it to double or int32, for example double( c) or int32( c).
Amjad Iqbal
Amjad Iqbal 2022-2-21
Dear @Arthur Reis
After applying above operation and using double(c) or int32, the image obtained is not binary and unable to get same signature given in primary image (but with 0, 1)
Amjad Iqbal
Amjad Iqbal 2022-2-21
I have to generate a binary image (e.g., 1 is land and 0 is sea)
In the primary image green color (with zero values) is land, and rest of image with yellow, red, blue is water with values < and > then 1.
Cris LaPierre
Cris LaPierre 2022-2-21
Consider sharing your data. You can attach it to your post using the paperclip icon.
Amjad Iqbal
Amjad Iqbal 2022-2-21
Dear @Cris LaPierre I have attached data file, since size is larger, I clipped small size.
Cris LaPierre
Cris LaPierre 2022-2-21
The challenge I see is that none of your data values exactly equal 1. You'll need to look at your data and decide what range of values you want to consider to represent land.

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Image Analyst
Image Analyst 2022-2-21

0 个投票

" I need to replace values greater and less than zero with zero (0) and replace all values = zero with 1. "
So why don't you just do
outputMatrix = inputMatrix == 0;

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