[Octave-bug-tracker] [bug #44118] imwrite saves wrong pixel values into jpg file

[H. G.]

URL:
  <http://savannah.gnu.org/bugs/?44118>

                 Summary: imwrite saves wrong pixel values into jpg file
                 Project: GNU Octave
            Submitted by: hardy
            Submitted on: Do 29 Jan 2015 16:20:58 GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.8.2
        Operating System: Any

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Details:

Here is a short script to demonstrate the behavior:


A = uint8([0 50 255; 1 3 6])
file='new.jpg';  
imwrite(A,file);
B = imread(file)


As you can see on the output of the command window, the values of B are not
equal to the values of A. Actually, the wrong pixel values are already saved
into the jpg file.

This error does NOT happen with png or tif image files.

Changing the data type to double does NOT help.

This happesn with the latest release (3.8.2) of Octave. Under Linux as well as
under Windows.




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