Apple - How to Install pdfimages in El Capitan?

You can install via Homebrew with the following command:

brew install poppler

Another command-line program that can extract bitmap images from PDF files is the command-line version of the Unarchiver app called 'unar'. (Doesn't need Homebrew or anything to install.) The command is simply unar filename.pdf

http://unarchiver.c3.cx/commandline

(The original GUI-based Unarchiver.app does this as well.)