Source code: Lib/imghdr.py
The imghdr module determines the type of image contained in a file or
byte stream.
The imghdr module defines the following function:
-
imghdr.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.
The following image types are recognized, as listed below with the return value
from 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 |
New in version 3.5: The exr and webp formats were added.
You can extend the list of file types imghdr can recognize by appending
to this variable:
-
imghdr.tests¶ A list of functions performing the individual tests. Each function takes two arguments: the byte-stream and an open file-like object. When
what()is called with a byte-stream, the file-like object will beNone.The test function should return a string describing the image type if the test succeeded, or
Noneif it failed.
Example:
>>> import imghdr
>>> imghdr.what('bass.gif')
'gif'