Image variants and automatic thumbnails
Product images ›Image variants
April 7, 2026Updated: April 7, 20263 min read23 views
How Theka generates optimized thumbnails and previews for images
Image variants
When you upload an image (JPEG, PNG, GIF, WebP, TIFF) or a PDF, Theka automatically generates optimized size variants.
Default variants
| Name | Max size | Use |
|---|---|---|
| thumb_sm | 150px | Compact lists, tables |
| thumb_md | 400px | Cards, grids |
| preview | 1200px | Preview, lightbox |
Custom presets
The administrator can define different presets for each document type. For example the "Product Image" type can have larger variants than the "Logo" type.
Regeneration
If presets are changed or the original generation failed, you can regenerate variants from the document detail page.
For PDF files, Theka generates variants from the first page of the document.