How to install the latest version of ImageMagick?

According to http://www.imagemagick.org/discourse-server/viewtopic.php?t=29006#p129405, there is a PPA that provides the 6.8.9.9 version of ImageMagick for Ubuntu 14.04 at https://launchpad.net/~isage-dna/+archive/ubuntu/imagick that you can try at your own risk:

sudo add-apt-repository ppa:isage-dna/imagick
sudo apt-get update
sudo apt-get upgrade

Compile from source.

1. First off, check the current version of imagemagick:

   $ identify -version
   Version: ImageMagick 6.8.9-9 Q16 x86_64 2018-09-28 http://www.imagemagick.org
   Copyright: Copyright (C) 1999-2014 ImageMagick Studio LLC
   Features: DPC Modules OpenMP
   Delegates: bzlib cairo djvu fftw fontconfig freetype jbig jng jpeg lcms lqr ltdl lzma openexr pangocairo png rsvg tiff wmf x xml zlib
   

   If it is already installed via apt-get and the version is old, remove it:

   sudo apt-get remove imagemagick
   

2. Create a src directory:

   mkdir ~/src
   cd ~/src
   

3. Download version 6.9.10-23 of Imagemagick source:

   wget http://www.imagemagick.org/download/ImageMagick-6.9.10-23.tar.gz
   

4. Install some packages from apt-get that are necessary for compiling from source:

   sudo apt-get install build-essential checkinstall
   

5. Untar source and cd into directory:

   tar xf ImageMagick-6.9.10-23.tar.gz
   cd ImageMagick-6.9.10-23/
   

6. Configure, make and checkinstall:

   ./configure
   make
   checkinstall
   

7. Update links/bindings:

   ldconfig
   

8. Verify and:

   $ identify -version
   Version: ImageMagick 6.9.10-23 Q16 x86_64 2019-01-02 https://imagemagick.org
   Copyright: © 1999-2019 ImageMagick Studio LLC
   License: https://imagemagick.org/script/license.php
   Features: Cipher DPC OpenMP
   Delegates (built-in): bzlib djvu fontconfig freetype gvc jbig jng jpeg lcms lqr 
   lzma openexr png tiff wmf x xml zlib
   

9. Party!