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58 lines
1.8 KiB
TeX
58 lines
1.8 KiB
TeX
\section{\module{imghdr} ---
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Determine the type of an image}
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\declaremodule{standard}{imghdr}
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\modulesynopsis{Determine the type of image contained in a file or
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byte stream.}
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The \module{imghdr} module determines the type of image contained in a
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file or byte stream.
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The \module{imghdr} module defines the following function:
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\begin{funcdesc}{what}{filename\optional{, h}}
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Tests the image data contained in the file named by \var{filename},
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and returns a string describing the image type. If optional \var{h}
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is provided, the \var{filename} is ignored and \var{h} is assumed to
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contain the byte stream to test.
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\end{funcdesc}
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The following image types are recognized, as listed below with the
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return value from \function{what()}:
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\begin{tableii}{l|l}{code}{Value}{Image format}
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\lineii{'rgb'}{SGI ImgLib Files}
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\lineii{'gif'}{GIF 87a and 89a Files}
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\lineii{'pbm'}{Portable Bitmap Files}
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\lineii{'pgm'}{Portable Graymap Files}
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\lineii{'ppm'}{Portable Pixmap Files}
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\lineii{'tiff'}{TIFF Files}
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\lineii{'rast'}{Sun Raster Files}
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\lineii{'xbm'}{X Bitmap Files}
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\lineii{'jpeg'}{JPEG data in JFIF format}
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\lineii{'bmp'}{BMP files}
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\lineii{'png'}{Portable Network Graphics}
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\end{tableii}
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You can extend the list of file types \module{imghdr} can recognize by
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appending to this variable:
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\begin{datadesc}{tests}
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A list of functions performing the individual tests. Each function
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takes two arguments: the byte-stream and an open file-like object.
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When \function{what()} is called with a byte-stream, the file-like
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object will be \code{None}.
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The test function should return a string describing the image type if
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the test succeeded, or \code{None} if it failed.
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\end{datadesc}
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Example:
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\begin{verbatim}
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>>> import imghdr
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>>> imghdr.what('/tmp/bass.gif')
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'gif'
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\end{verbatim}
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