pg_image
--------
This extension provides an IMAGE datatype for the storage of bitmap images,
which verifies that the image data is in a recognized format (PNG or JPEG)
and provides accessor functions for the image metadata (format, width, height)
and any EXIF metadata which is present.

The text representation is compatible with BYTEA columns;  an optional binary
format is also available which allows for a compact representation.

Depends on the GD library for image loading and manipulation.


Usage
-----
The IMAGE datatype can be added to a database using the Postgres extension
mechanism:

    CREATE EXTENSION pg_image;

Once installed, the pg_image extension provides the IMAGE datatype.  The type
I/O functions use the data: URI format (commonly used to include inline images
in HTML and CSS documents) for the image data.

Several functions and operators are provided for working with values of type
IMAGE:

    Function/Operator   Returns     Description
    -----------------   ---------   -----------------------------------------------
    width(IMAGE)        INTEGER     Width (in pixels) of the image.
    height(IMAGE)       INTEGER     Height (in pixels) of the image.
    filesize(IMAGE)     INTEGER     File size (in bytes) of the image.
    mimetype(IMAGE)     TEXT        Image's mimetype ("image/png" or "image/jpeg").
    imagedata(IMAGE)    BYTEA       The raw image data, in JPEG or PNG format.
    image(BYTEA)        IMAGE       Construct an IMAGE value from raw image data
                                    in JPEG or PNG format.  (TODO!)
    image_hash(IMAGE)   INT4        Hash value.
    = (IMAGE, IMAGE)    BOOLEAN     Equality.
    <>(IMAGE, IMAGE)    BOOLEAN     Inequality.


Build/install
-------------
To build (and install):
    make
    make install
    make installcheck

To build the .deb package:
    dpkg-buildpackage -b -uc -rfakeroot


Authors and Credits
-------------------
Andrew Tipton       andrew@kiwidrew.com

The base64 encoding/decoding functions are lightly modified copies of the
excellent Postgres functions by the same name.  (Which are unfortunately
not exposed in the public API except through a high-level wrapper.)

Thanks to malloc() labs limited (www.malloclabs.com) for supporting the
development of this module.


License
-------
This Postgres extension is free software;  you may use it under the same terms
as Postgres itself.