MATLAB: Exporting pixel data from image into text

arrayimageimage analysisimage processingImage Processing ToolboxMATLAB

Hello all,

I am completely new to Matlab but I am wondering if this is possible… I have an image which is 500×500, I can currently export the pixel data into a text file and results are exported like "1, 1 = (0, 0, 0)" but I want the origin(0,0) to be in the center of the image so that -250,-250 would be the result.

Not sure if this is making sense but any help would be appreciated.

Best Answer

[nr, nc, np] = size(YourImage);
[R, C] = ndgrid((1:nr)-floor(nr/2)-1, (1:nc)-floor(nc/2)-1);
Vec = @(M) double(M(:));
data = [R(:), C(:), Vec(YourImage(:,:,1)), Vec(YourImage(:,:,2)), Vec(YourImage(:,:,3))];
fid = fopen('TheOutputFileNameGoesHere.txt', 'wt');
fprintf(fid, '%d, %d = (%d, %d, %d)\n', data.');   %transpose is important
fclose(fid)

Related Solutions

MATLAB: How to export the pixel value of an jpg image to a .txt file

You forgot to mention, if you have imported the JPG already. And you did not specify the format of the txt file. While writing the pixel values is trivial, the re-creation of the image requires the dimensions also.

img = imread('YourImage.jpg');
fid = fopen('YourImage.txt', 'w');
if fid == -1, error('Cannot open file'); end
fprintf(fid, '%d %d %d ', size(img));  % Assuming it is an RGB image
fprintf(fid, '%g ', img(:));
fclose(fid);

The re-import:

fid = fopen('YourImage.txt', 'r');
if fid == -1, error('Cannot open file'); end
ImgSize = fscanf(fid, '%d %d %d ', 3);
ImgData = fscanf(fid, '%g ', Inf);
Img     = reshape(ImgData, ImgSize);
fclose(fid);

The file will be shorter, if you convert the floating point values to integers before writing:

ImgInt = round(Img * 255);

and a corresponding back-transformation after the reading.

BTW. Are you really sure that this is useful? imread seems to be more convenient.

MATLAB: Reading a .dat file with textread

jpg images are binary images, but textread() is for reading text files.

Does the .dat file perhaps contain the names of the images rather than the images themselves?

There is no standard format for .dat files: it is a suffix used by any program to hold any data. You need to know the internal structure of that particular .dat file in order to work with it. It might be pure text (most .dat files are not).

If you can upload a sample of the file, someone might have a look at it. http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers

Best Answer

Related Solutions

MATLAB: How to export the pixel value of an jpg image to a .txt file

MATLAB: Reading a .dat file with textread

Related Question