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How to visualise data value with x-y coordinate in an image

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RAJ DATTA
RAJ DATTA on 14 Sep 2019
Commented: RAJ DATTA on 16 Sep 2019
Hello, suppose I have x-y coordinate and z value as the grades of the points. How can I visualize my data in 2-D colormap ? (I want to show x-y cordinate and different colors for different values at every points inside the image). I am attachng sample data text file and regarding image.
Please help.

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Walter Roberson
Walter Roberson on 15 Sep 2019
I suspect you want griddedInterpolant()
Along with a colormap such as 'hot' or perhaps 'autumn'
RAJ DATTA
RAJ DATTA on 16 Sep 2019
yes. I found I need to interpolate to and a matrix should be created for [x,y, data]. only then I can make an image. Thank you sir for your idea.

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Answers (1)

Image Analyst
Image Analyst on 15 Sep 2019
Try something like
data = dlmread(filename, ' ');
x = data(:, 1);
y = data(:, 2);
grayLevel = data(:, 3);
grayImage = zeros(ceil(max(y)), ceil(max(x)));
for k = 1 : length(x)
row = round(y(k));
col = round(x(k));
grayImage(row, col) = grayLevel(k);
end
grayImage = mat2gray(grayImage);
imshow(grayImage, 'ColorMap', jet(256));
colorbar;

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Image Analyst
Image Analyst on 15 Sep 2019
Not only the blue, but for most of them. There are 181 pixels that are not zero. But most of your image locations do not have a gray level defined for them, so they are left as zero and appear as blue.
data = dlmread('md1.txt', ' ');
x = data(:, 1);
y = data(:, 2);
grayLevel = data(:, 3);
grayImage = zeros(ceil(max(y)), ceil(max(x)));
for k = 1 : length(x)
row = max([1, round(y(k))]);
col = max([1, round(x(k))]);
grayImage(row, col) = grayLevel(k);
fprintf('Assigning %d to row %d, column %d.\n', grayLevel(k), row, col);
end
minGL = min(grayImage(:))
maxGL = max(grayImage(:))
grayImage = mat2gray(grayImage);
imshow(grayImage, [], 'ColorMap', jet(256));
colorbar;

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