/Doc/library/imghdr.rst
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- :mod:`imghdr` --- Determine the type of an image
- ================================================
- .. module:: imghdr
- :synopsis: Determine the type of image contained in a file or byte stream.
- The :mod:`imghdr` module determines the type of image contained in a file or
- byte stream.
- The :mod:`imghdr` module defines the following function:
- .. function:: what(filename[, h])
- Tests the image data contained in the file named by *filename*, and returns a
- string describing the image type. If optional *h* is provided, the *filename*
- is ignored and *h* is assumed to contain the byte stream to test.
- The following image types are recognized, as listed below with the return value
- from :func:`what`:
- +------------+-----------------------------------+
- | Value | Image format |
- +============+===================================+
- | ``'rgb'`` | SGI ImgLib Files |
- +------------+-----------------------------------+
- | ``'gif'`` | GIF 87a and 89a Files |
- +------------+-----------------------------------+
- | ``'pbm'`` | Portable Bitmap Files |
- +------------+-----------------------------------+
- | ``'pgm'`` | Portable Graymap Files |
- +------------+-----------------------------------+
- | ``'ppm'`` | Portable Pixmap Files |
- +------------+-----------------------------------+
- | ``'tiff'`` | TIFF Files |
- +------------+-----------------------------------+
- | ``'rast'`` | Sun Raster Files |
- +------------+-----------------------------------+
- | ``'xbm'`` | X Bitmap Files |
- +------------+-----------------------------------+
- | ``'jpeg'`` | JPEG data in JFIF or Exif formats |
- +------------+-----------------------------------+
- | ``'bmp'`` | BMP files |
- +------------+-----------------------------------+
- | ``'png'`` | Portable Network Graphics |
- +------------+-----------------------------------+
- .. versionadded:: 2.5
- Exif detection.
- You can extend the list of file types :mod:`imghdr` can recognize by appending
- to this variable:
- .. data:: tests
- A list of functions performing the individual tests. Each function takes two
- arguments: the byte-stream and an open file-like object. When :func:`what` is
- called with a byte-stream, the file-like object will be ``None``.
- The test function should return a string describing the image type if the test
- succeeded, or ``None`` if it failed.
- Example::
- >>> import imghdr
- >>> imghdr.what('/tmp/bass.gif')
- 'gif'