After installing Imagemagick, I've tested it with jpg image, like this:

identify 1.jpg

But, I got this result:

identify: no decode delegate for this image format `1.jpg' @ error/constitute.c/ReadImage/550.

Then, I tried to add support for JPEG format by:

yum install libjpeg libjpeg-devel

but, I got:

Setting up Install Process
No package libjpeg available.
No package libjpeg-devel available.
Nothing to do

I thought I need to update the apt-get, I did:

apt-get install libjpeg libjpeg-devel

but, I got:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package libjpeg
E: Unable to locate package libjpeg-devel

Is there an easy way to get those libraries installed ? I am using Ubuntu 12.04.