Crate immeta

immeta allows one to load metadata from files of various image formats.

Some kinds of applications need to work with image metadata, e.g. resolution, color depth, whether the image is animated or not, etc, but do not need to access the actual image contents. This library tries to provide exactly that, unifying the interface for different image types under one umbrella. Because reading image metadata is far easier that decoding the pixels of the image, this library can be smaller and faster and support more formats than full-fledged image libraries.

Naturally, different image formats (JPEG, PNG, GIF, WebP, etc.) all have different types of metadata available within them. In fact, the only common piece of metadata between all of them is image resolution.

immeta can inspect an image file and load the metadata specific to this format. Metadata for each image format is exposed as a separate type; there is also a generic type which is used for dynamic image type detection. Naturally, it is possible to go from the generic type to some specific type (if it is the actual image type, of course).

Currently immeta can parse the following image formats:

• JPEG
• PNG 1.2
• GIF (both 87a and 89a)

Support for more types will come in future versions, as well as support for particular metadata kinds (e.g. EXIF tags in JPEG) which are not yet available.

Important note: this library only allows inspecting image metadata, not the image contents. That is, it does not perform decoding and does not provide access to pixels which the image consists of. If you need this functionality, consider using a library like image.

Modules

common
formats	Supported image types.
markers	Contains metadata marker types.

Structs

Dimensions

Represents image dimensions in pixels.

Enums

Error	Library-specific error type which is returned by metadata loading operations.
GenericMetadata	Represents metadata loaded from a file whose format was determined automatically.

Traits

LoadableMetadata

Provides several convenience functions for loading metadata from various sources.

Functions

load	Attempts to load metadata for an image contained in the provided input stream.
load_from_buf	Attempts to load metadata for an image contained in an in-memory buffer.
load_from_file	Attempts to load metadata for an image contained in a file identified by the provided path.

Type Definitions

Result

Library-specific result type.