How to install imgcat on iTerm2?
Just install "Shell Integration" and it will be automatically installed for you.

On the iTerm2 Menu, just click "Install Shell Integration"



You should then see the output indicating that imgcat is installed:

$curl -L https://iterm2.com/misc/install_shell_integration_and_utilities.sh | bash
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2694  100  2694    0     0   2890      0 --:--:-- --:--:-- --:--:--  2890
Downloading script from https://iterm2.com/misc/bash_startup.in and saving it to /Users/allan/.iterm2_shell_integration.bash...
Checking if /Users/allan/.bash_profile contains iterm2_shell_integration...
Downloading imgcat...
Downloading it2dl...
Adding aliases...
Done.
--------------------------------------------------------------------------------

The next time you log in, shell integration will be enabled.

You will also have these commands:
imgcat filename
  Displays the image inline.
it2dl filename
  Downloads the specified file, saving it in your Downloads folder.