Using imagemagick to crop and resize 100+ photos

I've been trying to incorporate Spanish video games into my language studies! While I play some Pokémon Platinum (in Spanish), I take photos of dialogue that I should study, and later turn those photos into Anki flashcards. But I ran into an issue: too many big photos.

Lately, I've been playing Pokémon Platino, a Latin American Spanish patch for Pokémon Platinum on the DS.

The problem is that when I take photos with my phone, they're taken in:

1. Excessively high resolution. My flashcards do not need Ultra HD photos.
2. Portrait mode, which leads to wasted space on the top and bottom.

I'm taking hundreds of photos, so with these issues, I end up taking gigabytes of photos in a session. Especially for the sheer quantity of images, I couldn't find a reliable bulk image processor online. I'm definitely not going to manually crop every single picture, girl!

Luckily, I found a free, convenient, and offline solution to both of these problems!

Bulk cropping and resizing with imagemagick

imagemagick is like the ffmpeg of images. It's a popular photo processing command-line tool that offers bulk image cropping and resizing.

Since it's a CLI tool, it's super easy to write an imagemagick command into a reusable script! I make the flashcards on my Windows PC, so I opted for a Windows batch file (🤮). The script requires a single argument, which is a path pointing to a directory of images taken from my phone. magick.exe first crops the top and bottom out of the image, and then downsizes the result into a 400x300 resolution.

if "%1"=="" goto argerr

magick.exe mogrify -crop 3472x2601+0+950 -resize 400x300 %1\*.jpg
@echo Done!
goto :eof

:argerr
@echo Requires a path argument!
exit /B 1

Running the script to crop/resize all images in the new-photos folder looks like this:

> optimize.bat .\new-photos\

On average, I observed 4.50 MB images become roughly 100 KB! That's a 95% file size reduction!!