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