How to read a raw format image data into a matrix??

I have the following old program for reading image into a matrix. But it is not working with new version Matlab.

How to modify this code?? Thanks!

x=zeros(512,512);
fid=fopen('d:\research\usc512\lenna','rb');
if(fid==-1)
  error('Error!');
end
for i=1:512
    x(i,:)=fscanf(fid,'%c',512);
end
fclose(fid);

Answer 1

[Walter Roberson]

That code is valid, if a bit wasteful. It does, though, look for a file d:\research\usc512\lenna that has no file extension, which is unusual in MS Windows. Windows Explorer by default hides file extensions but you can ask to reveal them. I suspect that you will find that the file does have an extension; if so then it needs to be specified in the fopen()

[filename, filepath] = uigetfile('d:\research\usc512', 'Select a file');
fullname = fullfile(filepath, filename);

fid = fopen(fullname, 'rb');
x = fread(fid, [512, 512], 'uint8=>double').' ;  %careful, it goes down columns first
fclose(fid);

[Huan-Sheng Wang]

That old code works on old version MATLAB! LENNA has no file extension. This LENNA contains raw data. When this old code running on new version MATLAB, it will quit when i=380. That's strange.

[Walter Roberson]

I read in lena.jpg and wrote out lenna (no file extension) from it using fwrite(). I then used the code you indicate to read it back in, changing only the path to the file. It works for me and produces an input identical to the original.

Which MATLAB version are you using, and which version of MS Windows?

Did you experiment with the code I posted?

[Huan-Sheng Wang]

The MATLAB version is R1024a. The MS Windows I am using is WIN7 64 bits. If I run the old code under R0124a, I got the message "Subscripted assignment dimension mismatch." when i=380. I will try your code later! Thank you very much!