I share a lot of screenshots for example in Slack. Pretty often I need to show before/after iterations, with or without annotations.

I recently made a little bash function that resides in my dotfiles to merge two images together, side by side.

Function

#!/usr/bin/env bash

# Merge two images side by side, then open in Preview
function mont() {
  montage -background '#336699' -geometry 100% ~/desktop/"$1" ~/desktop/"$2" ~/desktop/merged.png;
  open -a Preview ~/desktop/merged.png
}

Montage is a part of ImageMagick. Install it using brew install imagemagick

Usage

Example images

image.png

image2.png

mont image.png image2.png

I do this from ~/desktop

Result

A new image merged.png is created and opened in Preview. Convenient for adding annotations.