ImgsOptimizer

Lightweight batch image optimization daemon for Linux — automatically compresses JPEG and PNG files as they appear in a watched directory.

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How It Works

1. On start — scans the target directory and optimizes all images that haven't been processed yet
2. While running — listens for new files via inotifywait and optimizes them as they appear
3. Tracking — each processed file is marked with an extended filesystem attribute (optimized=yes) so it is never processed twice

new file detected
      │
      ▼
jpgpngoptimizer
  ├── JPEG → jpegoptim (lossless, strip metadata)
  └── PNG  → optipng → advpng → pngcrush (strip auxiliary chunks)
      │
      ▼
attr -s optimized -V yes <file>

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Scripts

Script	Description
imgsoptimizer	Main daemon — watches a directory and triggers optimization on new files
jpgpngoptimizer	Optimizes a single JPEG or PNG file
findimgswithoutattr	Scans a directory and optimizes all files not yet marked as optimized
imgsoptimizer-init	LSB-compliant init.d script for running the daemon as a system service

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Requirements

Install dependencies (Debian/Ubuntu):

sudo apt-get install jpegoptim optipng advancecomp pngcrush inotify-tools attr

Tool	Purpose
jpegoptim	Lossless JPEG compression, strips EXIF/metadata
optipng	PNG optimization (re-encodes with maximum compression)
advpng	Further PNG compression using zlib/7zip
pngcrush	Strips auxiliary PNG chunks (gamma, color profile, timestamps)
inotify-tools	Filesystem event monitoring (inotifywait)
attr	Read/write extended filesystem attributes

Filesystem requirement: the target partition must be mounted with the user_xattr option to support extended attributes.

# Example: enable xattr on mount
mount -o remount,user_xattr /dev/sdXY /mount/point

# Or add to /etc/fstab permanently:
# UUID=...  /mount/point  ext4  defaults,user_xattr  0 2

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Installation

1. Clone the repository:

git clone https://github.com/Incred/imgsoptimizer.git
cd imgsoptimizer
chmod +x imgsoptimizer jpgpngoptimizer findimgswithoutattr

The scripts automatically detect their own location, so they will find each other regardless of where you place them — no manual path editing required.

2. (Optional) Install as a system service:

Open imgsoptimizer-init and edit the three variables at the top of the file:

DAEMON=/usr/local/bin/imgsoptimizer   # Full path to the imgsoptimizer script
USER="www-data"                        # User to run the daemon as
WATCHING_DIR="/var/www/media/"         # Directory to watch for new images

Then install and start the service:

sudo cp imgsoptimizer-init /etc/init.d/imgsoptimizer
sudo chmod +x /etc/init.d/imgsoptimizer
sudo update-rc.d imgsoptimizer defaults
sudo service imgsoptimizer start

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Usage

Run the daemon (watches a directory for new images):

./imgsoptimizer /path/to/images/

Process existing files (one-time scan of a directory):

./findimgswithoutattr /path/to/images/

Optimize a single file:

./jpgpngoptimizer /path/to/image.jpg
./jpgpngoptimizer /path/to/image.png

Manage the service (if installed via init.d):

sudo service imgsoptimizer start
sudo service imgsoptimizer stop
sudo service imgsoptimizer status
sudo service imgsoptimizer restart

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Notes

• Optimization is lossless for both JPEG and PNG — no quality degradation
• JPEG files have their metadata (EXIF, IPTC) stripped during optimization
• PNG files have auxiliary chunks (gamma, color profile, timestamps) removed
• Logs are written to /var/log/imgsoptimizer.log when running as a service

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License

MIT © Incred