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Image Management

Learn how LZ SKU Sync automatically downloads, optimizes, and manages product images from Zoho Inventory.

Overview

LZ SKU Sync handles all aspects of product image management automatically:

  • ✅ Downloads images from Zoho as ZIP archives
  • ✅ Extracts and uploads to WordPress Media Library
  • ✅ Generates standard WordPress thumbnails
  • ✅ Prevents duplicate images
  • ✅ Assigns images to products and variations
  • ✅ Manages gallery images for variable products

How Image Download Works

Step-by-Step Process

  1. Fetch ZIP: Downloads all product images from Zoho
  2. Rate Limiting: 2-second delay between requests (respects Zoho's 100 req/min limit)
  3. Retry Logic: Up to 5 retries with 60-second backoff on rate limit errors
  4. Extract: Unzips images to temporary directory
  5. Upload: Adds images to WordPress Media Library
  6. Deduplicate: Checks MD5 hash to prevent duplicates
  7. Attach: Links images to product as featured or gallery
  8. Cleanup: Deletes temporary files

Image Optimization

Thumbnail Generation

WordPress standard thumbnail sizes are automatically created: - Thumbnail (150x150) - Medium (300x300) - Large (1024x1024) - Plus any custom sizes defined by your theme

Note

Image processing happens in the background via Action Scheduler to prevent timeouts.

Variable Product Image Handling

For variable products (product groups in Zoho), images are managed intelligently:

For Each Variation

  1. Each variation gets its own images based on its item_id
  2. Images are attached directly to the variation
  3. First image becomes the variation's featured image

For Parent Product

After all variations are processed:

  • Featured Image: First variation's first image
  • Gallery Images: Unique images from all variations (no duplicates)
  • Parent images set via separate Action Scheduler job

Preventing Duplicate Images

Images are tracked using MD5 hash to prevent uploading the same image multiple times:

How It Works

  1. Hash Calculation: MD5 hash generated from image file content
  2. Storage: Hash stored in database as _wzi_image_md5_{hash_value} = {attachment_id}
  3. Check Before Upload: Hash compared against existing media
  4. Reuse If Match: If hash exists, existing attachment ID is reused

Benefits

  • ✅ Saves storage space
  • ✅ Prevents database bloat
  • ✅ Faster sync (no redundant uploads)
  • ✅ Works across multiple syncs

Tip

If you delete an image from Media Library and then re-sync, it will be downloaded again since the hash is cleared.

Image Fields in Sync Settings

Control which image fields are synchronized:

  • Main product image
  • First image from Zoho becomes featured image
  • Shown on product listings and product page
  • Additional product images
  • All other images from Zoho added to gallery
  • Displayed in product image carousel

Note

Both options can be enabled/disabled independently in Product Settings.

Image Metadata

When images are uploaded, the plugin stores:

  • Original filename from Zoho
  • Alt text (product name)
  • Dimensions (width x height)
  • MD5 hash (for deduplication)
  • Product association

Background Processing

Image downloads and processing happen asynchronously:

Action Scheduler Jobs

  • wzi_upload_single_image - Uploads one image to WordPress
  • wzi_process_image_metadata - Generates thumbnails
  • wzi_assign_parent_images - Assigns images to variable product parent

Benefits

  • ✅ Prevents PHP timeouts
  • ✅ Handles large image batches
  • ✅ Continues even if you close browser
  • ✅ Full logging for debugging

Tip

Check image processing status at LZ SKU Sync > Sync Log → Search for Image Upload. See Sync Log Guide for search and filtering details.

Image Requirements

Zoho Inventory

  • Images must be attached to items in Zoho Inventory
  • Supported formats: JPG, PNG, GIF, WebP
  • Maximum recommended size: 5MB per image
  • Multiple images per product supported

WordPress

  • GD or Imagick PHP extension recommended (for image processing)
  • Uploads directory must be writable
  • Sufficient disk space for images
  • max_upload_size should accommodate ZIP files

Common Image Scenarios

Simple Product

  • All images from Zoho → WordPress Media Library
  • First image → Featured image
  • Other images → Gallery

Variable Product (Group)

  • Each variation downloads its own images
  • Parent product inherits variation images
  • Duplicates automatically filtered out

Product with No Images

  • No images downloaded
  • No featured image set
  • Product syncs normally (without images)

Troubleshooting Images

Images Not Downloading

Problem: Products sync but images are missing

Solutions:

  • ✅ Verify images exist in Zoho Inventory (Items → Attachments)
  • ✅ Check Sync Log for errors: LZ SKU Sync > Sync Log
  • ✅ Verify WordPress uploads directory permissions (should be 755)
  • ✅ Check Zoho API rate limits (100 requests/min)

Images Downloaded Multiple Times

Problem: Same image appears multiple times in Media Library

Solutions:

  • MD5 deduplication should prevent this
  • Check if hash is stored correctly: SELECT * FROM wp_postmeta WHERE meta_key LIKE '_wzi_image_md5%'
  • Ensure plugin version is up to date

Image Optimization Not Happening

Problem: Images not being optimized (e.g., WebP conversion)

Solutions:

  • The plugin generates standard WordPress thumbnails only
  • For advanced optimization (WebP, compression), use a dedicated image optimization plugin
  • Recommended plugins: ShortPixel, Imagify, EWWW Image Optimizer

Low Quality Images

Problem: Images look pixelated or compressed

Solutions:

  • Upload higher resolution images to Zoho Inventory
  • Check WordPress media settings: Settings > Media (increase max dimensions)
  • Original image quality comes from Zoho - ensure Zoho has high-res versions

Image Sync Taking Too Long

Problem: Image download is very slow

Explanation:

  • Rate limiting: 2 seconds between requests (Zoho API limit)
  • For 100 products with 3 images each = ~10 minutes minimum
  • This is intentional to comply with Zoho's API limits

Solutions:

  • Be patient - large catalogs take time
  • Images download in background (can close browser)
  • Check progress at LZ SKU Sync > Sync Log (see Sync Log Guide)

Best Practices

Before Syncing

  1. ✅ Upload high-quality images to Zoho Inventory
  2. ✅ Use descriptive image filenames
  3. ✅ Remove unnecessary images from Zoho to speed up sync

During Sync

  1. ✅ Let image processing complete in background
  2. ✅ Don't cancel sync during image downloads
  3. ✅ Monitor Action Scheduler for errors

After Sync

  1. ✅ Review products to ensure images are correct
  2. ✅ Delete unused media via Media > Library (if needed)
  3. ✅ Optimize remaining images with image optimization plugins (optional)

Next Steps

Support

Questions about image management?