Conversion of (129x7 complex double) to an Image

Question

Muhammad 2023-2-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1906355-conversion-of-129x7-complex-double-to-an-image

评论： DGM 2023-2-7

I have a variable s (129x7 complex double). I want to save it as an image. I have tried many ways but I can't save it.

for k=1:size(cm,2)
    s = spectrogram(cm(:,k));
    save(['Spectro_Subj' num2str(h) '_channel' num2str(i) '_window' num2str(k) '.mat'],'s')
end

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DGM 2023-2-4

Typical image formats (BMP,PNG,JPG) support unsigned integer (or logical) datatypes. Some (TIFF) can be wrangled into supporting floating-point numeric data, but you shouldn't expect anything to be able to read the file. No image format that I know of supports complex-valued numeric data. You may be able to store the components of the data in separate images (real and imag), or perhaps it may suffice to reduce it to magnitude only.

Long story short, if you have arbitrarily-scaled complex data and you want to save it as a typical image format, you'll have to decide on a means of preserving scale information, and you'll have to decide which components of the complex data you want to keep or how you want to encode them into a single real-valued integer array (perhaps magnitude/phase can be encoded as intensity/hue?).

Walter Roberson 2023-2-4

Tiff supports ComplexIEEEFP. However MATLAB's interface to libTiff does not support that.

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Answer 1

Image Analyst 2023-2-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1906355-conversion-of-129x7-complex-double-to-an-image#answer_1164425

编辑：Image Analyst 2023-2-7

在 MATLAB Online 中打开

Try exportgraphics

for k=1:size(cm,2)
    spectrogram(cm(:,k));
    baseFileName = sprintf('Spectro_Subject %d_channel %d_window %d.png', h, i, k);
    fullFileName = fullfile(pwd, baseFileName);
    fprintf('For k = %d, saving "%s".\n', k, fullFileName);
    exportgraphics(gca, fullFileName);
end

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Muhammad 2023-2-7

@Image Analyst thank you so much i will. In the mean time as you can see i segment the signal into 3.5s frame windows, i need to have time (0-3.5s) on x axis and Frequency on Y axis. Currently i am just getting samples and normalized frequency. please have a look into the below attachement.

DGM 2023-2-7

Note the only reason why I don't use exportgraphics() isn't because saveas() is better. I just run an older version, so I can't verify my example with something I can't run.

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