# Settings

## `THUMBNAIL_DEBUG`

- Default: `False`

When set to `True` the `ThumbnailNode.render` method can raise errors. Django recommends that tags never raise errors in the `Node.render` method but since sorl-thumbnail is such a complex tag we will need to have more debugging available.

## `THUMBNAIL_BACKEND`

- Default: `'sorl.thumbnail.base.ThumbnailBackend'`

This is the entry point for generating thumbnails, you probably want to keep the default one but just in case you would like to generate thumbnails filenames differently or need some special functionality you can override this and use your own implementation.

## `THUMBNAIL_KVSTORE`

- Default: `'sorl.thumbnail.kvstores.cached_db_kvstore.KVStore'`

Deprecated since version 12.11.0: Using any other KVStore than the Cached Db KVStore is deprecated. Please configure the cache that suits your use case at Django level and set this cache alias in `THUMBNAIL_CACHE`.

sorl-thumbnail needs a Key Value Store to How sorl-thumbnail operates. sorl-thumbnail ships with support for three Key Value Stores:

### Cached DB

`sorl.thumbnail.kvstores.cached_db_kvstore.KVStore`. This is the default and preferred Key Value Store. It uses the cache configured at the Django project level.

#### Features

- Fast persistent storage

- First query uses database which is slow. Successive queries are cached and if you use memcached this is very fast.

- Easy to transfer data between environments since the data is in the default database.

- If you get the database and fast cache out of sync there could be problems.

### Redis

From Django 4.0, you can configure a Redis cache at Django level and then use the Cached DB store while using the configured cache alias in the `THUMBNAIL_CACHE` setting. Therefore the Redis store in sorl-thumbnail and its associated `THUMBNAIL_REDIS*` settings maybe removed in the future.

`sorl.thumbnail.kvstores.redis_kvstore.KVStore`. It requires you to install a Redis server as well as a redis python client.

#### Features

- Fast persistent storage

- More dependencies

- Requires a little extra work to transfer data between environments

### Dbm

`sorl.thumbnail.kvstores.dbm_kvstore.KVStore`. A simple Key Value Store has no dependencies outside the standard Python library and uses the DBM modules to store the data.

#### Features

- No external dependencies, besides the standard library

- No extra components required, e.g., database or cache

- Specially indicated for local development environments

## `THUMBNAIL_KEY_DBCOLUMN`

- Default `'key'`

Since MSSQL reserved the `key` name for db columns you can change this to something else using this setting.

## `THUMBNAIL_ENGINE`

- Default: `'sorl.thumbnail.engines.pil_engine.Engine'`

This is the processing class for sorl-thumbnail. It does all the resizing, cropping or whatever processing you want to perform. sorl-thumbnail ships with four engines:

### PIL

`'sorl.thumbnail.engines.pil_engine.Engine'`. This is the default engine because it is what most people have installed already. Features:

- Easy to install

- Produces good quality images but not the best

- It is fast

- Can not handle CMYK sources

### Pgmagick

`'sorl.thumbnail.engines.pgmagick_engine.Engine'`. Pgmagick uses Graphics. Fatures:

- Not easy to install unless on linux, very slow to compile

- Produces high quality images

- It is a tad slow?

- Can handle CMYK sources

### ImageMagick / GraphicsMagick

`'sorl.thumbnail.engines.convert_engine.Engine'`. This engine uses the ImageMagick `convert` or GraphicsMagic `gm convert` command. Features:

- Easy to install

- Produces high quality images

- It is pretty fast

- Can handle CMYK sources

- It is a command line command, that is less than ideal,

### Wand

`'sorl.thumbnail.engines.wand_engine.Engine'`. This engine uses Wand, a ctypes-based simple ImageMagick binding for Python. Features:

- Easy to install

- Produces high quality images

- Can handle CMYK sources

- Works on Python 2.6, 2.7, 3.2, 3.3, and PyPy

## `THUMBNAIL_CONVERT`

- Default `'convert'`

Path to convert command, use `'gm convert'` for GraphicsMagick. Only applicable for the convert Engine.

## `THUMBNAIL_IDENTIFY`

- Default `'identify'`

Path to identify command, use `'gm identify'` for GraphicsMagick. Only applicable for the convert Engine.

## `THUMBNAIL_STORAGE`

- Default: `default`

The storage to use for the generated thumbnails, as an alias from the Django `STORAGES` setting. Optionally accepts a path to a Storage subclass.

## `THUMBNAIL_REDIS_URL`

The Redis database URL to connect as used by redis-py

When specified, other `THUMBNAIL_REDIS_*` connection settings will be ignored.

## `THUMBNAIL_REDIS_DB`

- Default: `0`

The Redis database. Only applicable for the Redis Key Value Store

## `THUMBNAIL_REDIS_PASSWORD`

- Default: `''`

The password for Redis server. Only applicable for the Redis Key Value Store

## `THUMBNAIL_REDIS_HOST`

- Default: `'localhost'`

The host for Redis server. Only applicable for the Redis Key Value Store

## `THUMBNAIL_REDIS_PORT`

- Default: `6379`

The port for Redis server. Only applicable for the Redis Key Value Store

## `THUMBNAIL_REDIS_TIMEOUT`

- Default: `3600 * 24 * 365 * 10`

Cache timeout for Redis Key Value Store in seconds. You should probably keep this at maximum or `None`.

## `THUMBNAIL_DBM_FILE`

- Default: `thumbnail_kvstore`

Filename of the DBM database. Depending on the DBM engine selected by your Python installation, this will be used as a prefix because multiple files may be created. This can be an absolute path.

## `THUMBNAIL_DBM_MODE`

- Default: `0x644`

Permission bits to use when creating new DBM files

## `THUMBNAIL_CACHE_TIMEOUT`

- Default: `3600 * 24 * 365 * 10`

Cache timeout for Cached DB Key Value Store in seconds. You should probably keep this at maximum or `None` if your caching backend can handle that as infinite. Only applicable for the Cached DB Key Value Store.

## `THUMBNAIL_CACHE`

- Default: `'default'`

Django configured cache alias to use for Cached DB Key Value Store. Defaults to the `'default'` cache but you can use any other cache configured in the Django project.

- `https://docs.djangoproject.com/en/stable/topics/cache/`

## `THUMBNAIL_KEY_PREFIX`

- Default: `'sorl-thumbnail'`

Key prefix used by the key value store.

## `THUMBNAIL_PREFIX`

- Default: `'cache/'`

The generated thumbnails filename prefix.

## `THUMBNAIL_FORMAT`

- Default: `'JPEG'`

Default image format, supported formats are: `'JPEG'`, `'PNG'`. This also implicitly sets the filename extension. This can be overridden by individual options.

## `THUMBNAIL_PRESERVE_FORMAT`

- Default: `False`

If `True`, the format of the input file will be preserved. If `False`, `THUMBNAIL_FORMAT` will be used.

## `THUMBNAIL_COLORSPACE`

- Default: `'RGB'`

Default thumbnail color space, engines are required to implement: `'RGB'`, `'GRAY'` Setting this to None will keep the original color space. This can be overridden by individual options.

## `THUMBNAIL_UPSCALE`

- Default: `True`

Should we upscale by default? `True` means we upscale images by default. `False` means we don’t. This can be overridden by individual options.

## `THUMBNAIL_QUALITY`

- Default: `95`

Default thumbnail quality. A value between 0 and 100 is allowed. This can be overridden by individual options.

## `THUMBNAIL_PROGRESSIVE`

- Default: `True`

Saves jpeg thumbnails as progressive jpegs. This can be overridden by individual options.

## `THUMBNAIL_ORIENTATION`

- Default: `True`

Orientate the thumbnail with respect to source EXIF orientation tag

## `THUMBNAIL_DUMMY`

- Default: `False`

This is a very powerful option which came from real world frustration. The use case is when you want to do development on a deployed project that has image references in its database. Instead of downloading all the image files from the server hosting the deployed project and all its thumbnails we just set this option to `True`. This will generate placeholder images for all thumbnails missing input source.

## `THUMBNAIL_DUMMY_SOURCE`

- Default `https://dummyimage.com/%(width)sx%(height)s`

This is the generated thumbnail whensource of the presented thumbnail. Width and Height is passed to the string for formatting. Other options are for example:

- `https://via.placeholder.com/%(width)sx%(height)s`

- `http://placekitten.com/%(width)s/%(height)s`

## `THUMBNAIL_DUMMY_RATIO`

- Default: `1.5`

This value sets an image ratio to all thumbnails that are not defined by width and height since we cannot determine from the file input (since we don’t have that).

## `THUMBNAIL_ALTERNATIVE_RESOLUTIONS`

- Default: `[]`

- Example: `[1.5, 2]`

This value enables creation of additional high-resolution (“Retina”) thumbnails for every thumbnail. Resolution multiplicators, e.g. value 2 means for every thumbnail of regular size x*y, additional thumbnail of 2x*2y size is created.

## `THUMBNAIL_FILTER_WIDTH`

- Default: `500`

This value sets the width of thumbnails inserted when running filters one texts that regex replaces references to images with thumbnails.

## `THUMBNAIL_URL_TIMEOUT`

- Default: `None`

This value sets the timeout value in seconds when retrieving a source image from a URL. If no timeout value is specified, it will wait indefinitely for a response.

## `THUMBNAIL_REMOVE_URL_ARGS`

- Default: `True`

This value sets if URL arguments will be removed from the source URL of the image we want to generate a thumbnail of. E.g. if our source image is at `<domain>/picture?height=600&width=600` a `True` value would instead attempt to generate a thumbnail from `<domain>/picture`.