| name | image-analysis |
| description | Reference for auction item image analysis — what to look for in photos of auction items, how to extract catalog-relevant information from images, and how the extension's AI image analysis works. |
| argument-hint | ["category or aspect"] |
Auction Item Image Analysis Reference
Use this skill when working on image analysis features, Claude Vision prompts, or photo-based cataloging. Focus on: $ARGUMENTS
How Image Analysis Works in the Extension
Architecture
Item images (up to 5 slots) → base64 encoding → Claude Vision API
↓
Structured JSON response:
- Title, description, condition
- Artist, period, materials
- Keywords, estimate, reserve
Image Slots (categorized)
| Slot | Purpose | What to extract |
|---|
| Front/Main | Primary identification | Object type, style, material, overall condition |
| Back/Reverse | Maker marks, construction | Stamps, signatures, labels, construction method |
| Markings | Stamps, hallmarks | Manufacturer, date, origin, purity (silver/gold) |
| Signatures | Artist identification | Name, date, numbering, technique notes |
| Condition | Damage documentation | Specific flaws, repairs, wear patterns |
Image Processing
- Images exceeding 5MB auto-resized via canvas (
_resizeBase64Image)
- Max dimension: 1400px (progressively reduced if still too large)
- Output: JPEG at 0.82 quality (reduced to 0.5 at minimum)
- Domain whitelist:
auctionet.com, images.auctionet.com, upload.wikimedia.org
What to Look For (by category)
Art & Paintings
- Signature: location (lower right, a tergo), legibility, full name vs initials
- Dating: exact year, decade, century — write exactly as on work
- Technique: oil on canvas, watercolor, mixed media, lithograph, etching
- Numbering: edition number for prints (e.g., "120/310")
- Frame: type, period (but NEVER report frame condition)
- Canvas/paper: condition, foxing, tears, restorations
- Size: height × width without frame
Furniture
- Style identification: gustavian, rococo, art deco, functionalist
- Construction: joinery type, original vs restored parts
- Wood type: visible in unfinished areas — only identify if confident
- Hardware: original vs replacement handles, locks, hinges
- Surface: veneer condition, inlay, painted decoration
- Stamps/labels: maker marks, often on underside or back
Silver & Gold
- Hallmarks: city mark, year mark, maker mark, assay mark
- Purity: sterling (925), 830, 18k, 14k — only from stamps, never guess
- Weight: essential for precious metals
- Engravings: monograms, presentation inscriptions (always mention in condition)
- Construction: filled base vs solid (affects weight relevance)
Glass & Ceramics
- Manufacturer marks: underside stamps, etched signatures
- Technique: blown, pressed, cut, etched, overlay
- Color: describe accurately for glass
- Condition: chips (nagg), hairline cracks (hårspricka), crazing
- Size: height and/or diameter
Rugs & Textiles
- Origin: Persian, Turkish, Scandinavian — from patterns and construction
- Construction: hand-knotted, machine-made, flatweave
- Material: wool, silk, cotton — from texture and sheen
- Condition: fringe wear, color fading, repairs, moth damage
- Size: always in title — length × width
Watches & Clocks
- Manufacturer & model: from dial and caseback
- Movement: automatic vs quartz (from caseback or movement view)
- Case material: steel, gold, gold-plated — from stamps
- Case size: diameter in mm
- Dial condition: patina, lume condition, text legibility
Weapons & Militaria
- EXTRA CAUTION — anti-hallucination rules are strictest here
- Only describe what is physically visible
- Never add historical context not explicitly present
- Never guess school names, regions, or periods from style
- Focus on: markings, inscriptions, materials, construction method
AI Prompt Patterns for Image Analysis
Hallucination Prevention
- "Describe ONLY what you can see in the image"
- "Do NOT infer historical period from style alone"
- "If uncertain about material, say 'appears to be' not 'is'"
- "Never fabricate maker names, dates, or provenance"
Extraction Priority
- Object identification — what is it?
- Material identification — what's it made of?
- Maker/artist identification — who made it? (from visible marks only)
- Condition assessment — what damage/wear is visible?
- Period estimation — when was it made? (conservative)
- Valuation clues — quality level, rarity indicators
Multi-Image Strategy
When multiple images are available:
- Cross-reference front view with detail shots
- Use back/underside for construction clues
- Use marking photos to confirm or identify maker
- Use condition photos to quantify damage described in main view
- Don't repeat information already captured from another image
Photography Guidelines (for reference)
Minimum Standards
- At least 3 photos per item
- Clean, neutral background (NCS S4000 N gray)
- Even lighting, no harsh shadows
- Include scale reference where helpful
Category-Specific Photo Requirements
| Category | Required shots |
|---|
| Furniture | Front, back (if old), marble top detail, interior |
| Art | Without frame (expensive), with frame, signature, back |
| Silver/Gold | Full view, hallmarks close-up, engravings |
| Porcelain | Full view, underside/marks, pattern detail |
| Rugs | Full spread, corner detail, back |
| Watches | Dial, caseback, movement (if accessible) |
| Services | Group shot, single piece detail, marks |
