When processing images, the result is encoded to the new image on the fly. The compression operations allow you to control this process. The format and quality operations affect loading speed and visual quality. The right balance of those helps improve conversions and bounce rates.
-/format/:format/
If any other image processing operation is applied,
the default format is auto (see how auto works).
Alternatively, you can use the -/format/ operation to convert an image
to one of the following formats:
jpeg is a lossy image format (good compression for photos). JPEG doesn’t
support an alpha channel; hence you can use the
setfill operation that sets a background
color. All browsers support JPEG.png is a lossless format (good compression only for graphics) with
alpha channel support. All browsers support PNG.webp is a modern format with more efficient compression than JPEG and with
alpha channel support. It works well for all images, yet not all
browsers and OSs support it.auto the default behavior; is an automatic image format selection based on
alpha channel presence and a client’s device and browser.preserve returns the image in the original format if it is PNG or JPEG,
otherwise coerces to PNG or JPEG. This option is useful
when you need to save the image, rather than display it to the end-user.auto works and prioritize image formatsFirst, the algorithm checks the Accept header with MIME types to figure out
what image format a client browser supports.
image/avif MIME type is supported by the client.image/webp MIME type is supported by the client.You can disable the selection of modern formats, specifically AVIF and WebP,
for your project in the Dashboard. Alternatively, you may consider adding the
-/format/preserve/ operation to a specific URL.
Note: auto works when you use primary Uploadcare storage (not S3
Bucket) and the default Uploadcare Image CDN domain ucarecdn.com.
Browsers that support WebP will load this image version, while others will display JPEG or PNG instead.
-/quality/:value/
Sets output quality for lossy formats (JPEG, WebP, and AVIF). Since actual settings vary from codec to codec and, more importantly, from format to format, we provide five simple tiers that are consistent across different formats and other settings and suit most cases of image distribution.
A higher quality level will typically result in a larger output file. However, setting the quality level higher than the original level of the uploaded image won’t increase your file size.
normal — the default behavior when no quality operation is applied.
The reasonable quality for 1x pixel density.better — can be used to render relatively small and detailed previews. ≈125%
file size compared to normal.best — can be used to deliver images close to their pristine quality
(e.g., for artwork). ≈170% file size.lighter — useful when applied to relatively large images to save traffic
without significant quality loss. ≈80% file size.lightest — highest compression ratio for high pixel ratio. ≈50% file size.Adaptive quality is enabled for all images in your project to automatically apply intelligent compression. Content-aware algorithms analyze each image to determine the maximum compression level that maintains visual quality, ensuring no noticeable artifacts.
Adaptive quality is enabled by default for projects created on or after August 4, 2025.
To use Adaptive quality:
-/preview/).A great approach for high pixel densities is to increase images resolution
and reduce quality at the same time. Compared to just increasing quality,
images will look clearer on all screens with nearly the same file size.
To adjust quality, you can use lighter and lightest presets.
-/progressive/yes/
-/progressive/no/
Returns a progressive image. In progressive images, data are compressed in
multiple passes of progressively higher detail. This is ideal for large images
that will be displayed while downloading over a slow connection allowing a
reasonable preview after receiving only a portion of the data.
The operation does not affect non-JPEG images; does not force image formats
to JPEG.
-/strip_meta/all/
-/strip_meta/none/
-/strip_meta/sensitive/
The original image often comes with additional information built into the image file. In most cases, this information doesn’t affect image rendering and thus can be safely stripped from the processed images to reduce image weight. Currently, you can only keep EXIF meta information. Other storage, such as XMP or IPTC, will always be stripped when creating a new processed image version.
all — the default behavior when no strip_meta operation is applied.
No meta information will be added to the processed file.none — uses the EXIF from the original file.
The orientation tag will be set to 1 (normal orientation).sensitive — uses the EXIF from the original file but skips geolocation.
The orientation tag will be set to 1 (normal orientation).If you need to restrict user access to EXIF information, please protect your images from editing.
Video files are much smaller than GIFs, without noticeable quality loss. Their delivery to end users is much faster. Gif to video operation converts animated image files, such as GIF, WebP, and HEIC, to video and transforms them on the fly. Learn more about animated images optimization.