How do I install imagemagick with homebrew?

brew install imagemagick

Don't forget to install also gs which is a dependency if you want to convert pdf to images for example :

brew install ghostscript

You could try:

brew update && brew install imagemagick

The quickest fix for me was doing the following:

cd /usr/local
git reset --hard FETCH_HEAD

Then I retried brew install imagemagick and it correctly pulled the package from the new mirror, instead of adamv.

If that does not work, ensure that /Library/Caches/Homebrew does not contain any imagemagick files or folders. Delete them if it does.

Answering old thread here (and a bit off-topic) because it's what I found when I was searching how to install Image Magick on Mac OS to run on the local webserver. It's not enough to brew install Imagemagick. You have to also PECL install it so the PHP module is loaded.

From this SO answer:

brew install php
brew install imagemagick
brew install pkg-config
pecl install imagick

And you may need to sudo apachectl restart. Then check your phpinfo() within a simple php script running on your web server.

If it's still not there, you probably have an issue with running multiple versions of PHP on the same Mac (one through the command line, one through your web server). It's beyond the scope of this answer to resolve that issue, but there are some good options out there.