Image Optimisation

Automatic image compression with Jpegli, AVIF, JXL, WebP, and intelligent lazy loading

Current guide

Overview

ProRank SEO's Image Optimisation combines local processing with optional plan-based cloud optimisation, responsive delivery, and WebP/AVIF generation. Available codecs depend on server libraries or cloud service availability, and savings vary by source image, quality setting, and output format.

Measured Savings

Compare original and delivered sizes; results vary by image and settings

Next-gen Formats

WebP and AVIF with standard fallbacks; advanced codecs require compatible processing

Lazy Loading & Alt Repair

Load images only when they enter the viewport and repair empty alt text from media metadata

Builder-Friendly Alt Text Repair

ProRank can backfill empty alt="" attributes for local media-library images at render time. This helps Elementor, widgets, and other builder output use the attachment alt text already saved in WordPress without editing every page manually.

License Tiers & Quotas

🏆 Agency License:100,000 images/year (8,333/month)

💼 Business License:20,000 images/year (1,666/month)

⭐ Pro License:5,000 images/year (416/month)

💳 Additional Credits:30,000 images for $5

Processing Methods

Cloud Optimisation

Sharp-based pipeline with libvips 8.17 + Jpegli/AVIF/JXL
pngquant → oxipng → ECT final pass for PNG
AI-powered smart cropping
Optional JPEG XL output when a compatible encoder is available
Encoding is offloaded; WordPress still uploads, queues, and receives results

Local Optimisation

On your server

GD Library or ImageMagick
Uses server-provided GD, Imagick, or compatible local binaries
Local mode keeps image processing on your WordPress host
Works offline
Limited by server resources

Automatic Fallback

ProRank automatically selects the best optimisation method based on your license and server capabilities. Cloud optimisation is preferred for Pro+ licenses, with automatic fallback to local processing if needed.

Managed Local Encoders (Pro+)

In ProRank SEO → Performance → Image Optimisation, the managed-encoder inventory reports each supported tool as managed by ProRank, available on the host, or not detected. It also shows the detected managed version and whether this host can execute command-line encoders.

Use Install or Remove beside an encoder in the inventory. Removing a managed copy lets normal host-tool detection take over again.
Installation is available only on supported Linux x86_64 or ARM64 hosts that allow command execution and writable generated-file storage.
An Install action succeeds only when ProRank's reviewed vendor manifest contains a matching platform-and-encoder entry. An empty or unmatched manifest does not provide a binary.
Before activation, the download is restricted to approved HTTPS hosts, checked as a compatible Linux executable, and verified against the manifest's SHA-256 checksum. A mismatch is discarded.

WP-CLI equivalents

# Show platform, managed paths, and host-fallback status
wp prorank binaries status

# Install one reviewed manifest build when available
wp prorank binaries install cwebp

# Remove only ProRank's managed copy
wp prorank binaries remove cwebp

The allowlist covers cwebp, avifenc, cjxl, cjpegli, pngquant, jpegoptim, optipng, oxipng, ect, and gifsicle. Availability still depends on a reviewed manifest entry for the current host platform.

Automatic Compression

Smart Compression Engine

Every image uploaded to your WordPress media library is automatically compressed using advanced algorithms that maintain visual quality while dramatically reducing file size.

Lossless Compression

Perfect for logos and graphics
No lossy quality reduction
Savings vary by source image and encoder
Preserves transparency

Lossy Compression

Ideal for photographs
Adjust quality and review representative images before bulk processing
Higher savings are possible at more aggressive quality settings
Adjustable quality levels

Evaluate Compression Results

JPEG Photos

Compare original and optimised bytes, then inspect representative detail at the configured quality.

PNG Graphics

Verify transparency, sharp edges, and colour fidelity as well as file-size reduction.

Modern Formats

Confirm the browser receives the intended WebP or AVIF asset and that the original fallback remains available.

Modern Format Conversion

WebP & AVIF Support

Automatically generates WebP and AVIF versions of your images, serving the most efficient format based on browser support while maintaining fallbacks for older browsers.

WebP Format

Often smaller than comparable JPEG output; measure on your images
Supports transparency
Supported by current major browsers, with original-format fallback
Lossless & lossy options

AVIF Format

Strong compression in the published benchmark; results vary by source and quality
Better quality at low bitrates
Supported by current major browsers, with original-format fallback
HDR support

Automatic Format Selection

Generated HTMLhtml

<!-- ProRank automatically generates picture elements with fallbacks -->
<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" alt="Description" loading="lazy" width="800" height="600">
</picture>

Smart Delivery

ProRank automatically detects browser capabilities and serves the most efficient format. Modern browsers get WebP/AVIF, while older browsers receive optimised JPEG/PNG.

Responsive Images

Responsive Image Support

ProRank works with WordPress's built-in responsive image system. When a CDN is configured, ProRank rewrites srcset URLs to serve optimised images from your CDN.

How It Works

ProRank works with WordPress's built-in responsive image srcset system
When a CDN is configured, ProRank rewrites srcset URLs for CDN delivery
Optional @2x retina image generation for high-DPI displays

Responsive Image Outputhtml

<!-- WordPress generates srcset with registered image sizes -->
<!-- ProRank rewrites URLs for CDN delivery when configured -->
<img 
  src="image.jpg"
  srcset="image-300x200.webp 300w,
          image-768x512.webp 768w,
          image-1024x683.webp 1024w"
  sizes="(max-width: 768px) 100vw, 1024px"
  alt="Responsive image"
  loading="lazy"
  width="1024"
  height="683">

Intelligent Lazy Loading

Progressive Image Loading

Images load only as they approach the viewport, reducing initial page weight and improving Core Web Vitals scores.

Native Lazy Loading

Browser-native implementation
No JavaScript required
SEO friendly
Automatic for all images

Smart Loading Features

Skip lazy load for above-fold
Progressive enhancement

LCP Optimisation

ProRank skips lazy loading on early images (first ~10 images on the page) to avoid delaying the Largest Contentful Paint element.

Cloud Processing Features

Cloud Image Processing

When using cloud optimisation, images are sent to the prorank.io processing API which handles format conversion, compression, and optional smart cropping.

Smart Cropping (Cloud)

Crop focus and face detection flags sent to cloud API
Processing handled server-side by prorank.io

Bulk Optimisation

Optimise Existing Images

Retroactively optimise all existing images in your media library with one click. Process thousands of images in the background without affecting site performance.

Bulk Processing Features

Background processing
Resume from interruptions
Progress tracking
Detailed statistics

Keep original backups
Restore originals anytime
Skip already optimised
Filter by date/size

Reliability & Recovery

Enterprise-Grade Reliability

Built with production resilience in mind, featuring automatic retry mechanisms, queue management, and comprehensive error recovery to ensure no image is left behind.

Retry Mechanism

Exponential backoff (1s, 2s, 4s)
3 automatic retry attempts
Failed queue for manual retry
Network error resilience

Backup & Recovery

Original image preservation
One-click restoration
Single backup copy per image

Production Safety

All optimisation operations are non-destructive. Original images are preserved in a backup directory, allowing instant restoration if needed. Failed optimisations are queued for automatic retry during the next processing cycle.

CDN Integration

Global Image Delivery

Automatically serve optimised images through your CDN with on-the-fly transformation support for dynamic resizing and format conversion.

Cloudflare

Cache purge via Zone API
CDN URL rewriting

BunnyCDN

Cache purge API
CDN URL rewriting

Custom CDN

URL rewriting
Origin pull
Cache control

Usage Monitoring & Statistics

Statistics Dashboard

The Image Optimisation settings page displays live statistics from your media library.

Displayed Metrics

Media Library Images — total images in your library
Modern-ready Images — images with WebP/AVIF versions generated
Space Saved — total bytes saved by optimisation
Optimisation Rate — percentage of eligible images optimised
Backup Storage Used — disk space used by original backups (when backups are enabled)

When cloud optimisation is active, quota usage and remaining credits are also displayed.

Available Statistics

Total images optimised
Total size saved
Average compression ratio
Cloud quota usage

Configuration

WordPress Settingsjavascript

// Access settings in WordPress Admin
// Settings > ProRank SEO > Performance > Image Optimisation

const imageSettings = {
  // Processing Method
  optimization_method: 'cloud', // 'cloud' | 'local' | 'auto'
  
  // Quality Settings
  jpeg_quality: 85,        // 1-100
  webp_quality: 80,        // 1-100
  avif_quality: 75,        // 1-100
  
  // Format Generation
  webp_enabled: true,      // Generate WebP versions
  avif_enabled: true,      // Generate AVIF versions
  
  // Processing Options
  optimize_on_upload: true,     // Auto-optimise new uploads
  background_mode: true,        // Use background processing
  preserve_metadata: false,     // Strip EXIF data
  
  // Advanced Options
  max_width: 2560,             // Maximum image width
  max_height: 2560,            // Maximum image height
  backup_originals: true,      // Keep original files
  auto_retry_failed: true,     // Retry failed optimisations
  
  // CDN Integration
  cdn_enabled: false,          // Enable CDN delivery
  cdn_provider: 'cloudflare',  // CDN provider
  cdn_url: '',                 // Custom CDN URL
};

Programmatic Controlphp

// Image optimisation is managed through the WordPress admin UI
// and REST API endpoints. Settings are configured at:
// ProRank SEO > Performance > Image Optimisation

// REST API endpoints:
// GET  /wp-json/prorank-seo/v1/image-optimization/settings
// POST /wp-json/prorank-seo/v1/image-optimization/settings
// POST /wp-json/prorank-seo/v1/image-optimization/optimize
// POST /wp-json/prorank-seo/v1/image-optimization/bulk-optimize
// POST /wp-json/prorank-seo/v1/image-optimization/restore

Performance Impact

What to Measure After Image Optimisation

Transfer size

Original vs delivered bytes

LCP

Lab and field change

Format delivery

WebP/AVIF and fallback

Visual quality

Representative-page review

Core Web Vitals Impact

Smaller image transfers can improve LCP when images are the bottleneck, but the result depends on hosting, theme, page composition, cache state, network, and the selected image settings. Validate with lab and field data.

Troubleshooting

Images not optimising?

• Check PHP memory limit (256MB recommended)
• Verify GD or ImageMagick is installed
• Check file permissions on uploads folder
• Review error logs for specific issues

WebP not serving?

Ensure your server supports WebP mime type and .htaccess rules are properly configured. Check browser dev tools network tab to verify WebP delivery.