Uploadcare CDN features on-the-fly image optimization, a large set of image transformations, and non-image file operations, such as getting file information or changing file delivery behavior.
You can find detailed specifications of all CDN operations in the URL API reference.
Key types of image operations are:
When applying any image operation, a new file is created (cached on our CDN, and not counted towards your storage limits). If not set, this file is encoded with the default quality and original format. However, you can adjust them to meet your requirements better.
Image processing operations have limits that you should consider.
List of supported image formats:
Some formats have several variations, and we support the most popular ones. Contact sales if you require additional formats or variations.
Without any image processing operation in the URL, CDN instructs
browsers to show images (
Content-Disposition: inline) and download other file
Content-Disposition: attachment). Browsers may not show all image formats,
HEIC formats. If you need to display an image, add any image
-/preview/ for instance.
When processing images, you must add at least one of the following operations via their respective URL directives:
Image processing operations can be applied to files smaller than 100 MB.
The file size limit can be increased individually. To do this, contact our sales team.
The dimensions you specify for the last operation should not exceed 3000x3000
pixels. You can go up to 5000x5000 pixels by explicitly setting
your image format to JPEG,
You can extend the output max resolution up to 8192x8192, and up to 16384x16384 for JPEGs in trade-off for increased latency. Contact our sales team to learn more about this option.
Any image transformation CDN URL is valid with an SVG file. Most operations
don't affect the response SVG body, while geometric operations (
scale_crop) change SVG attributes and work as expected.
To apply full range of operations on SVG file, it should be rasterized by
/rasterize/ operation. Read more about SVGs.
SVGs uploaded before May 26, 2021 still have
is_image: false and adding
processing operations to them will result in error. Contact support
to batch process previously uploaded files.
We don’t provide on-the-fly image processing for images greater than 75 Mpx in resolution: those are tagged as non-image files and can only be delivered via CDN as-is. Adding processing operations to non-image files will result in an error.
When the only image transformation you want is rotating, consider using the
preview control without any arguments. When
you use any of the transformations, we automatically rotate images according to
their EXIF orientation.
Animated images are treated as static by the transformations engine. Learn more about animated images optimization.
By default, CDN instructs browsers to show images and download other file types.
inline control allows you to change this behavior.
Your original filenames can be accessed via REST API.
Request to receive a JSON response with file parameters including
You can set an optional filename that users will see instead of the original name:
:filename should comply with file name conventions
and it should be a valid part of a URL. For example,
Returns file-related information, such as image dimensions or geotagging data in the JSON format.
In the second option,
json response will contain the
original key with the
info on your original image.
Same as the example above, but it returns data as the
type. The callback name should always be
uploadcare_callback. It should receive
the two following arguments:
id and a response object. For original files,
id is equivalent to their UUIDs. For processed files,
id is equivalent
to their URLs, excluding the last operation,
In the first case
id will be
c5b7dd84-c0e2-48ff-babc-d23939f2c6b4, in the
File info response includes a value of a perceptual hash calculated using pixel contents of an image. Perceptual hashing is a common fingerprinting technique to quickly compare images and find duplicates or similar images.
Uploadcare automatically calculates a 64-bit long perceptual hash value and returns it as a HEX string. In this example, the perceptual hash value is 940f5fd09aa48ddc:
It’s easy to find image duplicates by quickly comparing their perceptual hash values. To find similar images, it's important to compare perceptual hash values bitwise (Hamming distance). A small number of unmatched bits (e.g., up to 8 bits) will correspond to subtle changes in the visual contents, while non-similar images will usually have more than 8 different bits.
File groups serve as collections of files that help you organize content within your Uploadcare project. A group itself and files within it MUST belong to the same project.
Most often, file groups are used in the following cases:
- Multipage document conversion
- Creating video thumbnails
- Uploads multiple files simultaneously and then needs to display them together.
Learn more about file groups.