remiレポジトリを追加

$ rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

CentOS-Baseリポジトリを追加

$ vi /etc/yum.repos.d/CentOS-Base.repo

CentOS-Base.repo

[base]
name=CentOS-6 - Base
mirrorlist=http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

古いパッケージを削除

$ yum remove -y libtiff
$ yum remove -y graphviz
$ yum remove -y libwebp libwebp-devel
$ yum remove -y ImageMagick ImageMagick-devel ImageMagick-libs

新しいパッケージをインストール

$ yum install -y libtiff --enablerepo=remi,epel,base --disablerepo=amzn-main
$ yum install -y graphviz --enablerepo=remi,epel,base --disablerepo=amzn-main
$ yum install -y libwebp libwebp-devel --enablerepo=epel --disablerepo=amzn-main
$ yum install -y ImageMagick6 ImageMagick6-devel ImageMagick6-libs --enablerepo=remi,epel,base