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

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.

Answer 1

[Image Analyst]

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, []);

[Amjad Iqbal]

Perfect, It works, with what i required, now it's all about siffting and get more accurate results.

Many thanks dear @Image Analys

Answer 2

[Cris LaPierre]

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

[Amjad Iqbal]

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]

You can then convert it to double or int32, for example double( c) or int32( c).

[Amjad Iqbal]

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]

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]

Consider sharing your data. You can attach it to your post using the paperclip icon.

[Amjad Iqbal]

Dear @Cris LaPierre I have attached data file, since size is larger, I clipped small size.

[Cris LaPierre]

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.

Answer 3

[Image Analyst]

" 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;