ThumbHash

Generates a ThumbHash for every image file and stores it with the file. A ThumbHash is a placeholder of about 30 characters that clients decode into a blurred preview while the image loads.

Features

• Adds a thumbhash field to file entities.
• Generates the hash when an image file is saved for the first time or replaced.
• Downscales with an image style first, so it works with GD and ImageMagick. SVG is skipped.
• Can generate the hashes during cron instead of on save.
• Drush command for existing files.

Post-Installation

No configuration is needed. Run drush thumbhash:generate once for existing images (options: --limit, --force, --queue).

Settings are at /admin/config/media/thumbhash: the image style used for downscaling, and whether to generate the hashes during cron.

The module does not display the hashes. Read them with:

• PHP: $file->get('thumbhash')->value
• JSON:API: the thumbhash attribute of file resources
• Core REST: thumbhash[0].value, once the entity:file resource is enabled

The hash describes the original image, so it won't match image styles that crop.

Additional Requirements

• Drupal 11.2 or later
• srwiez/thumbhash, which Composer installs for you

Similar projects

• Blurhash: calculates a BlurHash on every render and doesn't store it.
• Image Blurry Placeholder: adds a tiny background image in the core image formatters. It provides no hash for APIs.