Romain Lespinasse

    Batch Resize Images on macOS via CLI (The Native Way)

    Posted on 2 mins

    MacOS Terminal Sips

    Table of Contents

    If you often need to resize dozens of images tucked away in various subdirectories. While apps like Photoshop or Lightroom are powerful, they are overkill for a simple task: resizing all png files to a maximum of 200px.

    Forget installing heavy dependencies like ImageMagick. macOS comes with a built-in “secret weapon” called Sips (Scriptable Image Processing System).

    The Scenario

    You have a project structure like this:

    You want to resize these to 200px (max side) and save them as _200px.png in the same folders, keeping the originals intact.

    The One-Liner Solution

    Open your terminal, navigate to your root folder, and run:

    find . -name "*.png" -exec sh -c 'sips -Z 200 "$1" --out "${1%.png}_200px.png"' _ {} \;

    Breaking Down the Command

    To understand what’s happening under the hood, let’s look at the components:

    Command PartPurpose
    find .Searches the current directory and all subfolders.
    -name "*.png"Filters only the files ending with your specific suffix.
    sips -Z 200Resizes the image so the largest dimension is 200px (preserving aspect ratio).
    --out ...Specifies the output path so we don’t overwrite the original.
    ${1%.png}_200px.pngA shell trick to strip the .png extension and append our new suffix.

    Why Sips?

    Sips is remarkably fast because it is optimized for the macOS file system and hardware. Unlike other tools, it:

    1. Respects Color Profiles: It uses Apple’s ColorSync technology.

    2. Zero Install: It has been part of macOS for decades.

    3. Smart Scaling: Using the -Z flag ensures your images never look “stretched” as it maintains the original proportions.

    Pro Tip: If you want to overwrite the original files instead of creating new ones, simply use:

    find . -name "*.png" -exec sips -Z 200 {} \;

    Summary

    Next time you’re preparing thumbnails for a gallery or optimizing assets for a website, don’t reach for a GUI. The power of the macOS CLI is right at your fingertips.