Converting Cartesian Coordinates to Binary image

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Mohanad Alkhodari 2020-6-14

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评论： Ameer Hamza 2020-6-21

采纳的回答： Ameer Hamza

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Hello

I have two vectors of X and Y cartesian values in +/-, how to convert them to a binary image of 0's and 1's

Thank you.

I attached my plot.

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Aditya Verma 2020-6-14

Hi, Could you specify how you want to map X and Y coordinates to the binary image. If I understand it correctly you want to create a 2-D matrix with binary values (Binary Image).

Mohanad Alkhodari 2020-6-14

Yes, I have the values as X and Y cartesian coordinates.

I want to convert them to pixel values. Like a 2D binary image where a 1 is located on the each location (X,Y).

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Ameer Hamza 2020-6-14

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Something like this

x = randn(1, 5000); % generate random points
y = randn(1, 5000);
img_dimension = [500 500]; % [width height]
img = zeros(img_dimension);
xt = floor(rescale(x, 1, img_dimension(2))); % convert x-y in range of image coordinates
yt = floor(rescale(y, 1, img_dimension(1)));
idx = sub2ind(img_dimension, yt, xt);
img(idx) = 1;
imshow(img)

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Mohanad Alkhodari 2020-6-21

编辑：Mohanad Alkhodari 2020-6-21

A circle of radius 0.8 covers more space than a circle of radius 0.2 when converting them from cartesian to binary.

With the above code, both circles are converted for a 500x500 for example and have the same size.

How can I convert to binary while preserving the scaling differences?

Ameer Hamza 2020-6-21

在 MATLAB Online 中打开

You can make the circle small and large by specifying the range of rescale() function

xt = floor(rescale(x, 100, img_dimension(2)-100)); % convert x-y in range of image coordinates
yt = floor(rescale(y, 100, img_dimension(1)-100));

create a circle between 100 to 400 pixels, i.e., leave 100 pixels on all sides unoccupied.

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Thiago Henrique Gomes Lobato 2020-6-14

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This is an general example you could use:

Cartesian = [ 10,1;
              15,10];
imSize=20;   
binaryImage= false(imSize);
Cartesian(:,2) = imSize-(Cartesian(:,2)-1); % Comment if you want zero at the top-left corner
for idx=1:size(Cartesian,1)
    binaryImage(Cartesian(idx,2),Cartesian(idx,1)) = true; % Note that X-Y index are inverted in indexing
end
figure,imshow(binaryImage)