ImageMagick suddenly installed

I was taking a look at my installed programs, when I saw a program called ImageMagick, I took a look at it in the Ubuntu Software Center, and it's a program to manipulate images.

That's OK, but I never installed that! I saw that I installed that approx. 1 month ago (May 25).

Just to be sure, did it came with an update or something like that?

In addition to the above answer, you can have some checks.

From your Software Center you can know the recent installed or updated apps.

And you can know which apps have imagemagick as dependency so you can know which app had installed it.

apt-cache rdepends imagemagick

sample output:

Reverse Depends:
  inkscape
    graphicsmagick-imagemagick-compat
  formatjunkie
    graphicsmagick-imagemagick-compat
  playonlinux
    graphicsmagick-imagemagick-compat
  lives
    graphicsmagick-imagemagick-compat
  variety
    graphicsmagick-imagemagick-compat
 |ejabberd
    graphicsmagick-imagemagick-compat
  imagemagick:i386
 |qt4-qmlviewer

From man apt-get

rdepends pkg...
           rdepends shows a listing of each reverse dependency a package has.

Imagemagick was installed, because it is required by another program that you recently (May 25) installed.

No voodoo, no magic. ;)