I am trying to use imshow to take data in a .txt file and print out the image made from the data.

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ssmith 2021-10-26

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https://ww2.mathworks.cn/matlabcentral/answers/1572118-i-am-trying-to-use-imshow-to-take-data-in-a-txt-file-and-print-out-the-image-made-from-the-data

编辑： ssmith 2021-10-27

采纳的回答： DGM

So far my code looks like this

a = dlmread('data.txt');

imshow(a);

But when I go to run the code I get an error saying "Error using abs too many input arguments." The .txt file has a ton of data points inside it and I made sure to save the .txt file in the same folder as my code so I am not sure why it is not able to read my data.

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DGM 2021-10-26

How is the data formatted in the text file? What is the size of a?

It would probably help to just attach the text file.

ssmith 2021-10-26

The data is formatted as (x, y, z, grayscale) The file is too large to attach the file.

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DGM 2021-10-26

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https://ww2.mathworks.cn/matlabcentral/answers/1572118-i-am-trying-to-use-imshow-to-take-data-in-a-txt-file-and-print-out-the-image-made-from-the-data#answer_817028

编辑：DGM 2021-10-26

I'm going to guess that this is the same homework assignment. If not, similar operations should apply. The example only shows how to rectify the image from the vectorized positional and intensity information. You'll have to figure out how to read the data from the file into the corresponding vectors and deal with the output scaling/casting as mentioned.

https://www.mathworks.com/matlabcentral/answers/1572038-create-image-from-pixels-using-two-vectors-and-their-grayscale-value

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DGM 2021-10-27

编辑：DGM 2021-10-27

The last comment was run entirely in-browser. What you see is exactly how I ran it. There shouldn't be anything that can cause anything to be dumped to console. All the lines are terminated with ";" to suppress output. If you missed a terminating semicolon, it would definitely take a while to dump 5.3 million lines to console.

Before trying to wrangle the whole data file, can you replicate the above behavior with the attached test file cmanvec.txt? Does that one display correctly?

If cmanvec.txt does not display, but dumps a bunch of garbage to console, then there is possibly a file conflicting with imshow() or something else.

If cmanvec.txt displays fine, but your image does not, then there's something else going on. If there is some unforeseen difference between my test file and yours (other than the sheer size), it might simply be easiest to zip the text file and upload it somewhere off-site. The attachments here on the forum only allow 5MB, but I'm guessing that your text file should be somewhere around 15MB once compressed. We can cross that bridge if necessary.

DGM 2021-10-27

在 MATLAB Online 中打开

I don't know why you'd get an error about a function/variable called "first". There isn't anything in the code called "first".

If you don't have mat2gray(), I'm guessing you don't have Image Processing Toolbox. You can do this instead for that line:

%A = mat2gray(a(:,4)); % normalize (needs IPT)
A = normalize(a(:,4),'range'); % normalize without IPT

ssmith 2021-10-27

编辑：ssmith 2021-10-27

That worked! Thank you so much for your help!!!

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