Automatic
auto
The auto
parameter helps you automate a baseline level of optimization across your entire image catalog. Currently, it has four different methods:
- Compression
- Visual enhancement
- File format conversion
- Redeye removal
If necessary for your image needs, you can override the settings that auto
represents, either on a per-image basis or in your code. For example, auto=compress
removes color profile metadata, but if it's necessary for your site, you can append a different value for cs
in your image URL such as cs=origin
or cs=srgb
.
Note: auto=format
is available as a Default Parameter for paying customers. Customers on our Free plans will be prompted to upgrade their account when attempting to add auto=format
as a Default parameter.
auto
values can be combined with comma separation, e.g. auto=compress,enhance
. Additionally, it is the only parameter that can be combined by reiteration, e.g. auto=compress&auto=enhance&auto=format
.
auto=compress
When auto=compress
is set, imgix will apply best-effort techniques to reduce the size of the image. This includes altering our normal processing algorithm to apply more aggressive image compression.
If auto=format
is included in the query, it will be respected. In this case, images will be served in AVIF format whenever possible while still applying compression. When AVIF is not supported, the image will be served as a WebP. If the WebP format is not supported, images that contain transparency will be served in a PNG8 format (if supported) and all others will be served as JPEG. The quality standard (q
) is set to 45.
Note: We strive to reduce file size while maintaining as much visual information as possible, so the operations applied are subject to change. This becomes visible on images using a high gamut range as seen in the below examples. Adding cs=origin
will resolve color issues by adding the original color space back. Additionally, the default quality standard can be overridden by using the q
parameter.
Note:
When used in conjunction with fm
for non-animated assets, auto=compress
will override the fm
parameter and will use a JPEG or PNG file depending on if an alpha channel is present
auto=enhance
When auto=enhance
is set, the image is adjusted using the distribution of highlights, midtones, and shadows across all three channels—red, green, and blue (RGB). Overall, the enhancement gives images a more vibrant appearance.
The adjustment affects individual images differently, and works best with editorial photography, stock photography, and user-generated content for social media applications.
auto=true
When auto=true
is set, imgix wil automatically adjust your asset by applying additional parameters. To start imgix will apply auto=enhance
to your asset.
Additionally, if you have crop=faces
set and apply auto=true
imgix will automatically apply auto=redeye
.
auto=format
When auto=format
is set, imgix determines whether the image can be served in a better format by a process called automatic content negotiation. It compiles the various signals available to us—including headers, user agents, and image analytics—to select the optimal image format for your user. This format is served back and the image is correctly cached.
The auto=format
logic will attempt to serve images in AVIF when supported. When AVIF is not supported, the image will be served as WebP. If the WebP format is not supported, it will serve the file as JPG or PNG.
The fallback logic can be modified by adding auto=compress
and/or specifying a fallback format with fm
. When used in conjunction with each other, fm
takes priority over auto=compress
. For example, specifying auto=format&fm=jpg
works only as a fallback parameter while auto=compress&fm=jpg
functions as an override for the file type set by auto=format
.
To learn more about auto=format
and auto content negotiation, read our tutorial.
Firefor 66+ warning
Starting with Firefox version 66, auto content negotation will only occur when an image is being rendered on a webpage. It will not occur when opening a single image in the browser.
Safari WebP Rendering Warning
A small percentage of WebP images will not render correctly in IOS 14 & Safari >= 14 due to a systems frameworks issue (opens in a new tab) under WebKit .
Because of this, auto=format
will return either a JPEG or a PNG in affected Safari versions.
Safari >=16.4 AVIF Support
Prior to September 2024, imgix served WebP images to Safari browsers when auto=format
was applied, due to stability concerns. As of September 2024, imgix now serves AVIF images to Safari browsers on version 16.4 or later when auto=format
is used.
auto=redeye
When auto=redeye
is set, red-eye removal is applied to any detected faces.
No Base64 Variant
This parameter does not accept base64-encoded values. All values must be provided as standard UTF8, url-encoded strings.