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Image Optimization Analysis

Free

Enhance SEO and performance through image audits.

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Free · Opens the source repo

What Image Optimization Analysis does

Image Optimization Analysis is a skill designed for developers and web designers focused on improving the SEO and performance of images on their websites. This tool conducts a comprehensive audit of images, checking critical factors such as alt text, file sizes, formats, responsive images, lazy loading practices, and more. By utilizing this skill, users can ensure that their images are not only visually appealing but also optimized for search engines and user experience.

The skill evaluates the presence and quality of alt text, ensuring that all images are described appropriately and include relevant keywords without falling into keyword stuffing. It also assesses file sizes against recommended thresholds for different image categories, providing guidance on how to compress images without sacrificing quality. Furthermore, it analyzes image formats, recommending modern formats like WebP and AVIF for better compression and browser compatibility, while also checking for the correct implementation of the <picture> element for fallback support.

In addition to these checks, the skill provides insights into responsive image handling, lazy loading practices, and measures to prevent cumulative layout shift (CLS). By ensuring that images are properly sized and lazy loaded only when appropriate, users can enhance their website's performance metrics, which are crucial for SEO rankings. The skill also emphasizes the importance of descriptive file names and CDN usage to further optimize image delivery.

Overall, Image Optimization Analysis is a valuable tool for anyone looking to improve their website's image SEO and performance, making it essential for web developers and designers aiming to create fast, efficient, and search-friendly websites.

When to use it

Use this skill when conducting an image audit or when optimizing images for better SEO and performance on a website.

When not to use it

This skill may not be suitable for users who do not manage image-heavy websites or require simple image editing tools.

What you can build with it

Conducting an Image Audit

Use this skill to perform a thorough analysis of all images on a website, identifying areas for optimization.

Improving SEO Rankings

Leverage the insights from this skill to enhance image SEO, leading to better search engine rankings.

Optimizing for Performance

Utilize the skill to ensure images are optimized for performance, reducing load times and improving user experience.

How to install Image Optimization Analysis

View source

1. Install with the skills CLI

npx skills add agricidaniel/claude-seo/seo-images --agent claude-code

2. Or install it manually

Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.

Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs

Inside SKILL.md

Written by agricidaniel

Image Optimization Analysis

Checks

Alt Text

  • Present on all <img> elements (except decorative: role="presentation")
  • Descriptive: describes the image content, not "image.jpg" or "photo"
  • Includes relevant keywords where natural, not keyword-stuffed
  • Length: 10-125 characters

Good examples:

  • "Professional plumber repairing kitchen sink faucet"
  • "Red 2024 Toyota Camry sedan front view"
  • "Team meeting in modern office conference room"

Bad examples:

  • "image.jpg" (filename, not description)
  • "plumber plumbing plumber services" (keyword stuffing)
  • "Click here" (not descriptive)

File Size

Tiered thresholds by image category:

Image CategoryTargetWarningCritical
Thumbnails< 50KB> 100KB> 200KB
Content images< 100KB> 200KB> 500KB
Hero/banner images< 200KB> 300KB> 700KB

Recommend compression to target thresholds where possible without quality loss.

Format

FormatBrowser SupportUse Case
WebP97%+Default recommendation
AVIF92%+Best compression, newer
JPEG100%Fallback for photos
PNG100%Graphics with transparency
SVG100%Icons, logos, illustrations

Recommend WebP/AVIF over JPEG/PNG. Check for <picture> element with format fallbacks.

Recommended <picture> Element Pattern

Use progressive enhancement with the most efficient format first:

<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" alt="Descriptive alt text" width="800" height="600" loading="lazy" decoding="async">
</picture>

The browser will use the first supported format. Current browser support: AVIF 93.8%, WebP 95.3%.

JPEG XL: Emerging Format

Third-party reporting and Wikipedia describe a Rust-based JPEG XL decoder as shipped in Chrome 145 stable (2026-02-10) behind the chrome://flags/#enable-jxl-image-format flag, not enabled by default; no Google-owned confirmation was retrieved in the fact pack. Because default support is not confirmed, it is not yet practical for production web delivery. Keep serving AVIF/WebP with JPEG fallback and monitor.

Responsive Images

  • srcset attribute for multiple sizes
  • sizes attribute matching layout breakpoints
  • Appropriate resolution for device pixel ratios
<img
  src="image-800.jpg"
  srcset="image-400.jpg 400w, image-800.jpg 800w, image-1200.jpg 1200w"
  sizes="(max-width: 600px) 400px, (max-width: 1200px) 800px, 1200px"
  alt="Description"
>

Lazy Loading

  • loading="lazy" on below-fold images
  • Do NOT lazy-load above-fold/hero images (hurts LCP)
  • Check for native vs JavaScript-based lazy loading
<!-- Below fold - lazy load -->
<img src="photo.jpg" loading="lazy" alt="Description">

<!-- Above fold - eager load (default) -->
<img src="hero.jpg" alt="Hero image">

Detected lazy-loader methods (lazy_method field)

scripts/parse_html.py classifies each image's lazy-loading mechanism via the lazy_method field on every image entry. Five values:

lazy_methodSignal detectedCommon stack
nativeloading="lazy" HTML attributeModern browsers, plain HTML
perfmattersdata-perfmatters-src/-srcset OR class perfmatters-lazyWordPress + Perfmatters plugin
ewwwdata-ewww-src / data-eio OR class lazyload-eioWordPress + EWWW Image Optimizer
js-genericdata-src / data-lazy-src / data-original / data-srcset OR class lazyload/lazyloaded/lazyLazysizes, vanilla-lazyload, jQuery plugins
noneNeither attribute nor class signalPage is not lazy-loading this image

When auditing image SEO, report lazy_method alongside loading so users know whether their site is using a JS-driven lazy-loader (in which case the native loading="lazy" attribute is intentionally absent, that is not a regression).

fetchpriority="high" for LCP Images

Add fetchpriority="high" to your hero/LCP image to prioritize its download in the browser's network queue:

<img src="hero.webp" fetchpriority="high" alt="Hero image description" width="1200" height="630">

Critical: Do NOT lazy-load above-the-fold/LCP images. Using loading="lazy" on LCP images directly harms LCP scores. Reserve loading="lazy" for below-the-fold images only.

decoding="async" for Non-LCP Images

Add decoding="async" to non-LCP images to prevent image decoding from blocking the main thread:

<img src="photo.webp" alt="Description" width="600" height="400" loading="lazy" decoding="async">

CLS Prevention

  • width and height attributes set on all <img> elements
  • aspect-ratio CSS as alternative
  • Flag images without dimensions
<!-- Good - dimensions set -->
<img src="photo.jpg" width="800" height="600" alt="Description">

<!-- Good - CSS aspect ratio -->
<img src="photo.jpg" style="aspect-ratio: 4/3" alt="Description">

<!-- Bad - no dimensions -->
<img src="photo.jpg" alt="Description">

File Names

  • Descriptive: blue-running-shoes.webp not IMG_1234.jpg
  • Hyphenated, lowercase, no special characters
  • Include relevant keywords

CDN Usage

  • Check if images served from CDN (different domain, CDN headers)
  • Recommend CDN for image-heavy sites
  • Check for edge caching headers

Output

Image Audit Summary

MetricStatusCount
Total Images-XX
Missing Alt TextXX
Oversized (>200KB)⚠️XX
Wrong Format⚠️XX
No Dimensions⚠️XX
Not Lazy Loaded⚠️XX

Prioritized Optimization List

Sorted by file size impact (largest savings first):

ImageCurrent SizeFormatIssuesEst. Savings
...............

Recommendations

  1. Convert X images to WebP format (est. XX KB savings)
  2. Add alt text to X images
  3. Add dimensions to X images
  4. Enable lazy loading on X below-fold images
  5. Compress X oversized images

Image SERP Analysis

When DataForSEO MCP is available, enhance the image audit with competitive data.

/seo images serp <keyword>

Cross-reference on-page images with Google Images SERP rankings.

Workflow:

  1. Fetch Google Images results via serp_google_images_live_advanced (depth=100)
  2. Extract: top domains, image types, alt text patterns
  3. Output competitor image SERP landscape

Output:

RankDomainTitle/AltImage URLPage URL
1example.com"Blue running shoes...".../shoes.webp/products/...

Analysis includes:

  • Domain dominance: which sites own the most image positions (top 10 by count)
  • Alt text patterns: common title/alt patterns in top-ranking images
  • Format distribution: WebP vs JPEG vs PNG in top results
  • Opportunity score: keywords where you have page rankings but no image presence

If DataForSEO MCP is not available, inform user and suggest installing the extension.


Image File Optimization

Optimize image files for SEO: format conversion, metadata injection, compression.

/seo images optimize <path>

Optimize image file(s) for web and SEO. Converts to WebP/AVIF, injects IPTC metadata, compresses, and generates responsive variants.

Tools used (in order of preference):

  • exiftool -- EXIF/IPTC/XMP read/write (install: sudo apt install libimage-exiftool-perl)
  • cwebp -- WebP conversion (install: sudo apt install webp)
  • ImageMagick convert -- Format conversion, resizing (pre-installed on most systems)
  • FFmpeg -- Fallback for format conversion (pre-installed)

Before running: Check which tools are available with which exiftool cwebp convert ffmpeg.

Format Conversion

Convert images to modern formats with metadata preservation:

# WebP (recommended default) - with metadata preserved
cwebp -q 82 -metadata all input.jpg -o output.webp

# WebP via ImageMagick (fallback if cwebp not installed)
convert input.jpg -quality 82 output.webp

# AVIF via FFmpeg (slower encode, best compression)
ffmpeg -i input.jpg -c:v libaom-av1 -crf 30 -still-picture 1 output.avif

# Responsive variants (400w, 800w, 1200w)
convert input.jpg -resize 400x -quality 82 image-400.webp
convert input.jpg -resize 800x -quality 82 image-800.webp
convert input.jpg -resize 1200x -quality 82 image-1200.webp

Metadata Injection (IPTC for Google Images Display)

Google Images displays IPTC Creator, Credit Line, and Copyright in search results. This is NOT a ranking factor but can improve Google Images display and brand attribution.

With exiftool (preferred):

# Read all metadata
exiftool image.jpg

# Inject IPTC + XMP metadata for Google Images rich results
exiftool \
  -IPTC:ObjectName="Product Photo Description" \
  -IPTC:Caption-Abstract="Detailed image description" \
  -IPTC:By-line="Brand Name Photography" \
  -IPTC:Credit="Brand Name" \
  -IPTC:CopyrightNotice="Copyright 2026 Brand Name" \
  -IPTC:Source="brandname.com" \
  -XMP:Title="Product Photo Description" \
  -XMP:Description="Detailed image description" \
  -XMP:Creator="Brand Name Photography" \
  -XMP:Rights="Copyright 2026 Brand Name" \
  image.jpg

# Batch inject to all images in directory
exiftool -overwrite_original \
  -IPTC:By-line="Brand Name" \
  -IPTC:CopyrightNotice="Copyright 2026 Brand Name" \
  *.jpg *.webp *.png

With ImageMagick (fallback):

identify -verbose image.jpg | head -50

convert input.jpg \
  -set comment "Product Photo Description" \
  -set IPTC:2:80 "Brand Name Photography" \
  -set IPTC:2:116 "Copyright 2026 Brand Name" \
  output.jpg

Note: WebP supports EXIF and XMP but not IPTC natively. For WebP files, use XMP fields instead of IPTC. exiftool handles this conversion automatically.

AI-Generated Images: DigitalSourceType (Merchant Center requirement)

For product images produced by generative AI, Google Merchant Center requires IPTC DigitalSourceType: TrainedAlgorithmicMedia metadata. This is an operational policy requirement, not a ranking factor: feeds missing this label on AI-generated imagery can be disapproved.

Primary source (Merchant Center AI-generated content policy): https://support.google.com/merchants/answer/14743464 (the ai-optimization-guide does not document DigitalSourceType/IPTC/Merchant labeling.)

Audit command:

# Audit a directory for the IPTC label (counts: missing, ai, captured, etc.)
claude-seo run iptc_ai_label.py audit ./images/ --json

# Audit a single image
claude-seo run iptc_ai_label.py audit ./hero.webp --json

# Inject the AI label into an image
claude-seo run iptc_ai_label.py inject ./ai-hero.webp \
    --source-type trainedAlgorithmicMedia

# Other vocabulary values:
#   compositeSynthetic               (mix of captured + AI elements)
#   algorithmicMedia                 (created purely by algorithm, NOT from sampled training data)
#   compositeWithTrainedAlgorithmicMedia (e.g. AI inpainting/outpainting over real media)
#   digitalCapture                   (fully captured photograph)

Raw exiftool equivalents (for ad-hoc usage):

# Inject manually
exiftool \
  -XMP-iptcExt:DigitalSourceType="https://cv.iptc.org/newscodes/digitalsourcetype/trainedAlgorithmicMedia" \
  ai-generated-product.jpg

# Audit: find images missing the label across a directory
exiftool -if 'not $XMP-iptcExt:DigitalSourceType' \
  -filename -DigitalSourceType *.jpg *.webp *.png

Google extracts these IPTC DigitalSourceType values:

  • trainedAlgorithmicMedia: fully AI-generated (use this for diffusion-model product imagery)
  • compositeSynthetic: mixes captured + AI-generated elements
  • algorithmicMedia: created purely by an algorithm, not from sampled training data
  • compositeWithTrainedAlgorithmicMedia: composite of trained algorithmic media + other media (e.g. AI inpainting/outpainting over a real photo)
  • digitalCapture: fully captured photograph (note: digitalCapture is not on Google's extracted-values list, but is a valid IPTC value)

Provenance signals (consumer-facing): SynthID watermarks and C2PA Content Credentials are emerging signals for AI media identification. Treat product-surface coverage as subject to change unless verified from a current Google-owned source. This is detection/transparency, not an extra required Merchant feed field beyond IPTC DigitalSourceType.

Licensable images: to earn the Licensable badge, supply EITHER structured data (ImageObject with the license property + acquireLicensePage for the "Get this image" link) OR embedded IPTC photo metadata (Licensor URL / Web Statement of Rights). Cross-link seo-schema for the ImageObject markup.

Discovery note: image discovery now includes visual search fan-out across Lens / AI Mode / Circle to Search (Gemini multimodal scene/object understanding), so images surface via scene, objects, and materials, not alt text alone. No new published image-SEO lever yet; keep descriptive alt text + clean structured data.

When /seo images optimize is run on AI-generated assets, prompt the user to confirm the source type and inject the matching IPTC value automatically.

For AI-generated product titles and descriptions, Google Merchant Center also requires the AI-generated text to be separately specified and labeled in the feed. This is enforced at the feed layer, not the page layer, flag this in cross-reference with seo-ecommerce.

Metadata Audit

# Quick audit with exiftool
exiftool -IPTC:all -XMP:all -EXIF:ImageDescription image.jpg

# Batch audit - find images missing IPTC Creator
exiftool -if 'not $IPTC:By-line' -filename *.jpg *.webp *.png

Full Optimization Pipeline

For maximum image SEO, run this pipeline on each image:

  1. Audit existing metadata: exiftool -IPTC:all -XMP:all image.jpg
  2. Inject IPTC/XMP metadata: Creator, Copyright, Description
  3. Convert to WebP: cwebp -q 82 -metadata all image.jpg -o image.webp
  4. Generate responsive variants: 400w, 800w, 1200w
  5. Verify metadata preserved: exiftool image.webp
  6. Generate <picture> HTML: AVIF > WebP > JPEG fallback chain

What Matters vs What Doesn't for Google Images

FactorImpactWhere to Set
Alt textCRITICAL (ranking)HTML <img alt="">
FilenameHIGH (ranking)File system (descriptive, hyphenated)
Page contextHIGH (ranking)Surrounding HTML content
File size/speedMEDIUM (indirect via CWV)Compression + format conversion
IPTC Creator/CopyrightLOW (display only)Image file metadata
EXIF camera dataNONEIrrelevant for SEO
IPTC KeywordsNONEGoogle ignores these

Error Handling

ScenarioAction
URL unreachableReport connection error with status code. Suggest verifying URL and checking if site requires authentication.
No images found on pageReport that no <img> elements were detected. Suggest checking if images are loaded via JavaScript or CSS background-image.
Images behind CDN or authenticationNote that image files could not be directly accessed for size analysis. Report available metadata (alt text, dimensions, format from markup) and flag inaccessible resources.
exiftool not installedFall back to ImageMagick for metadata. Recommend: sudo apt install libimage-exiftool-perl
cwebp not installedFall back to ImageMagick or FFmpeg for WebP conversion. Recommend: sudo apt install webp
DataForSEO MCP not availableSkip Image SERP Analysis section. Note extension is not installed.

Frequently asked questions about Image Optimization Analysis

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