I am unable to install the octave-image:i386 package. To solve this issue, I installed dependencies but I got the same error after that:

The following packages have unmet dependencies:
 octave-image:i386 : Depends: octave:i386 (>= 4.0.0) but it is not going to be installed

Can anyone please help me regarding this issue?

pagla@pagla-Inspiron-3521:~$ sudo apt-cache policy octave octave-image
  Installed: 4.0.2-1ubuntu5~octave~trusty1
  Candidate: 4.0.2-1ubuntu5~octave~trusty1
  Version table:
 *** 4.0.2-1ubuntu5~octave~trusty1 0
        500 http://ppa.launchpad.net/octave/stable/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status
     3.8.1-1ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
  Installed: 2.4.0-1~octave~trusty1
  Candidate: 2.4.0-1~octave~trusty1
  Version table:
 *** 2.4.0-1~octave~trusty1 0
        500 "http:ppa.launchpad.net/octave/stable/ubuntu/ trusty/main amd64 Packages"
        100 /var/lib/dpkg/status
     2.2.0-3 0
        500 "http/us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages"
  • Edit the question and include the output of apt policy octave octave-image command
    – Anwar
    Nov 19, 2016 at 13:46
  • it showed "invalid operation policy" Nov 19, 2016 at 13:51
  • 1
    Are you using Ubuntu? Which version? If that doesn't work use apt-cache policy octave octave-image instead
    – Anwar
    Nov 19, 2016 at 13:52
  • it showed "invalid operation policy" Nov 19, 2016 at 13:53
  • 2
    Also you seem to be using 64bit OS, why you need i386 packages? Those are for 32bit
    – Anwar
    Nov 19, 2016 at 14:21

1 Answer 1


First you were trying to install 32bit packages on 64-bit Ubuntu. That is not necessary. Leave the i386 part from the package name and just use octave-image.

Secondly, to be able to use rgb2gray function, you need to import the package where that function is defined. The package is image as revealed as par this thread. Also you need to load the package using pkg load image command first. Check this Stackoverflow question also.

Hope this will help.

  • @Sagittarius Glad it helped. Thanks to you too!
    – Anwar
    Nov 19, 2016 at 15:08

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