JPEG Resizer Script

This is a macOS-compatible Bash script that compresses .jpg and .jpeg images to ensure they are less than a user defined KiB threshold, using both native and external tools.

Description

This script:

• Recursively finds all .jpg / .jpeg images in a specified folder.
• Tries compressing images using macOS’s built-in sips tool.
• If that fails, it uses ImageMagick to iteratively reduce image quality and resolution until the file size is strictly under 200 KiB.
• Saves all resized/compressed images in a separate resized/ folder, preserving your original files.

Requirements

• macOS
• Bash
• ImageMagick (for fallback compression)

Install ImageMagick (if not already installed)

brew install imagemagick

Usage

1. Edit the Script

Open the script and set the correct folder path in the FOLDER variable:

FOLDER="/your/path/to/images"

2. Run the Script

chmod +x resize_images.sh
./resize_images.sh

Output

• Processed images are saved in a subfolder called resized inside your original folder:

  /your/path/to/images/resized/
  

• Each image is guaranteed to be < 200 KiB.

• Original images are not modified.

Compression Strategy

The script uses a two-step strategy:

1. Primary Compression with sips:

   • Tries low, then normal, then high quality settings.

2. Fallback Compression with ImageMagick:

   • Starts at 90% quality and 100% scale.
   • Gradually reduces quality and then scale until the file is under 200 KiB.

This ensures the best possible image quality while keeping file sizes within the limit.

Limitations

• Only supports .jpg and .jpeg files (case-insensitive).
• Currently supports macOS only (due to sips and stat -f%z usage).
• May reduce image quality or dimensions significantly if original images are large.

License

This script is free to use and modify. No warranties provided — use at your own risk.