Enhance Website Performance: Free Image Optimizer for Your Site

Modern cover image showcasing the concept of WebP image optimization for enhanced web performance, featuring symbols of fast-loading websites, the WebP format icon, and visual indicators like speedometers and arrows, designed in a clean, contemporary style for web developers and digital marketers.

In the age of digital media, the performance of your website can significantly impact user engagement, search engine rankings, and overall user experience. One of the key factors in website performance is the optimization of images. WebP, a modern image format developed by Google, offers superior compression and quality characteristics compared to traditional formats like JPEG and PNG. This guide provides a comprehensive approach to converting and optimizing images to WebP format for free, ensuring your website loads faster without sacrificing image quality.This is especially useful for websites using CMS systems like WordPress or Drupal where additional libraries, plugins or modules can have big impact on a site’s performance. This image optimizer will be equally helpful as other premium plugins.

Why Image Optimization Matters

  • Faster Page Load Times: Optimized images load faster, providing a better user experience.
  • Improved SEO Rankings: Search engines favor fast-loading websites, leading to better visibility.
  • Reduced Bandwidth Consumption: Smaller image files use less bandwidth, saving costs and resources.

Prerequisites to create Image Optimizer Script

Before you start, ensure you have ImageMagick installed on your system. It’s a powerful tool for image processing, supporting a variety of formats including WebP. Mac users can easily install ImageMagick using Homebrew with the following command:

Open Terminal and use Homebrew to install ImageMagick:

brew install imagemagick

Follow these instructions to install brew if you dont have it already.

Automating Image Optimization

The essence of this guide is a bash script that simplifies the conversion of images to WebP format. This script allows for batch processing, customizable quality settings, and the removal of metadata to further reduce file sizes. Hence the reason I call it Image Optimizer.

Key Features of the ‘Image Optimizer’ Script

  • Custom Quality Settings: Control the balance between image quality and file size.
  • Batch Processing: Convert multiple images in a directory for efficiency.
  • Metadata Stripping: Remove unnecessary metadata to minimize image file sizes.

Image Optimizer script:


# Function to display usage instructions
usage() {
    echo "Usage: $0 [-s size] [-d directory | -i image]"
    echo "  -s size       : Resize image to specified size (e.g., 1200x900)"
    echo "  -d directory  : Directory containing images to be converted"
    echo "  -i image      : Single image file to be converted"
    exit 1

# Default values

# Parse command line options
while getopts 's:d:i:' flag; do
    case "${flag}" in
        s) SIZE="${OPTARG}" ;;
        d) DIRECTORY="${OPTARG}" ;;
        i) IMAGE="${OPTARG}" ;;
        *) usage ;;

# Check if no options were provided
if [ -z "$SIZE" ] && [ -z "$DIRECTORY" ] && [ -z "$IMAGE" ]; then

# Function to convert image
convert_image() {
    local image=$1
    local output_dir="/path/to/output/images"
    local size=$3

    # Extract filename without extension
    filename=$(basename -- "$image")

    # Convert to WebP, resize, strip metadata, and save
    echo "Converting $image to WebP format..."
    magick convert "$image" -resize "$size" -quality $QUALITY -strip "$output_dir/$filename.webp"

# Create output directory if it doesn't exist
mkdir -p "$OUTPUT_DIR"

# Process images
if [ ! -z "$DIRECTORY" ]; then
    for image in "$DIRECTORY"/*.{jpg,png,jpeg}; do
        if [ -f "$image" ]; then
            convert_image "$image" "$OUTPUT_DIR" "$SIZE"
elif [ ! -z "$IMAGE" ]; then
    if [ -f "$IMAGE" ]; then
        convert_image "$IMAGE" "$OUTPUT_DIR" "$SIZE"
        echo "File $IMAGE does not exist."
        exit 1

echo "Conversion complete."

How to Use the Script

  • Save the script to a file, e.g., image_optimizer.sh.
  • Make it executable: chmod +x image_optimizer.sh.
  • Run it with your desired options, for example, to convert all images in a directory to 1200×900 pixels, use: ./image_optimizer.sh -s 1200x900 -d /path/to/images.
  • Or to to convert a single image in a directory, use: ./image_optimizer.sh -s 1200x900 -i image.jpeg
  • Finally you can just run the script without any option to see the instruction on how to use it, like this: ./image_optimizer.sh
  • Default quality I have added is 70, you can change it to your desired option ranging from 1 to 100.

Find the Right Balance between Quality and Filesize – Different options with Image Optimizer

Experiment with Quality Settings

The -quality parameter is a straightforward way to impact file size and quality. I’ve set it to 70, which is a good starting point, but depending on your needs, you might experiment with slightly lower values. Even a small change, like going to 65 or 60, can significantly reduce file size with minimal perceptible loss in quality for web use.

Adjust the Resize Parameters

If the images are being displayed at specific maximum dimensions on your website, ensure you’re resizing them to these dimensions. Serving images at their displayed size reduces unnecessary data load. The -resize option can be fine-tuned to match your exact needs.

Use Lossless Compression

For images where quality is paramount, consider using lossless compression with WebP. This can be achieved by specifying -define webp:lossless=true in your command. While lossless WebP files will be larger than their lossy counterparts, they will still be significantly smaller than equivalent PNGs.

Fine-tune Encoding Settings

WebP offers several encoding options that can be adjusted to optimize file size:

  • Near Lossless Compression: By using -define webp:near-lossless=60, you can achieve almost lossless quality with a reduced file size. The value can range from 0 (maximum compression) to 100 (no compression), allowing you to find the right balance.
  • Smart Subsampling: Activating smart subsampling with -define webp:auto-filter=true allows the encoder to decide the best filter type on a per-frame basis, which can reduce file size without a noticeable drop in quality.

Remove Metadata with Image Optimizer Script

We’re already using -strip to remove metadata, which is excellent. This removes unnecessary information such as EXIF data, which doesn’t affect visual quality but contributes to file size.

Testing and Iteration

Optimization is often about finding the right balance for your specific use case. Use tools like Google’s PageSpeed Insights, which can provide specific recommendations for your images and website. Regularly test different settings to find the best compromise between quality and file size. You can also modify the script by changing arguments settings for image optimizer and extend it to your needs.


Optimizing your images for the web doesn’t have to be a chore. By leveraging the WebP format and the power of ImageMagick, you can easily enhance your website’s performance. This guide aims to equip you with the knowledge and tools to improve your site’s load times for free, making your content more accessible and enjoyable for your audience.

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