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python-3.7.4-docs-html/_sources/library/imghdr.rst.txt

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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.
+
+**Source code:** :source:`Lib/imghdr.py`
+
+--------------
+
+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=None)
+
+   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.
+
+   .. versionchanged:: 3.6
+      Accepts a :term:`path-like object`.
+
+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         |
++------------+-----------------------------------+
+| ``'webp'`` | WebP files                        |
++------------+-----------------------------------+
+| ``'exr'``  | OpenEXR Files                     |
++------------+-----------------------------------+
+
+.. versionadded:: 3.5
+   The *exr* and *webp* formats were added.
+
+
+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('bass.gif')
+   'gif'
+