How to visualize data with MATLAB memmapfile?

Question

I am trying to read some data from a file, and output it as just raw data. The file is an image, and the output file I am writing data 1 row at a time.

In matlab, I do the following:

bin_path = 'myfile.bin';
m = memmapfile(bin_path, 'Format', {'uint16', [5000 5000], 'im'});
disp(m)
figure, imagesc(m.Data.im), colormap(gray)

To try to display the data, thinking I'd get an image. However, it is not an image, it is just a bunch of black and gray and white lines.

Is the matlab portion of this set up correctly?

Answer 1

This looks like it might work, if your file consists of exactly 5000x5000x2 bytes, each representing a pixel in a square image. Using memmapfile is unusual--in fact, I didn't even know that function existed in Matlab. It would be much more typical to simply use fread to read a raw image. If your image is in a standard file format (JPG, PNG, etc), use imread .

Assuming that your image is really 5000 x 5000 x uint16, you might be suffering from an endianness problem. Try using fopen and fread to get the data; Matlab's fopen accepts an argument telling it whether to do endianness translation.