39.12. jpeg — Read and write JPEG files
Deprecated since version 2.6: The jpeg module has been removed in Python 3.
The module jpeg provides access to the jpeg compressor and decompressor
written by the Independent JPEG Group (IJG). JPEG is a standard for compressing
pictures; it is defined in ISO 10918. For details on JPEG or the Independent
JPEG Group software refer to the JPEG standard or the documentation provided
with the software.
A portable interface to JPEG image files is available with the Python Imaging
Library (PIL) by Fredrik Lundh. Information on PIL is available at
http://www.pythonware.com/products/pil/.
The jpeg module defines an exception and some functions.
-
exception
jpeg.error
Exception raised by compress() and decompress() in case of errors.
-
jpeg.compress(data, w, h, b)
Treat data as a pixmap of width w and height h, with b bytes per pixel.
The data is in SGI GL order, so the first pixel is in the lower-left corner.
This means that gl.lrectread() return data can immediately be passed to
compress(). Currently only 1 byte and 4 byte pixels are allowed, the
former being treated as greyscale and the latter as RGB color. compress()
returns a string that contains the compressed picture, in JFIF format.
-
jpeg.decompress(data)
Data is a string containing a picture in JFIF format. It returns a tuple
(data, width, height, bytesperpixel). Again, the data is suitable to pass
to gl.lrectwrite().
-
jpeg.setoption(name, value)
Set various options. Subsequent compress() and decompress() calls
will use these options. The following options are available:
| Option |
Effect |
'forcegray' |
Force output to be grayscale, even if input
is RGB. |
'quality' |
Set the quality of the compressed image to
a value between 0 and 100 (default
is 75). This only affects compression. |
'optimize' |
Perform Huffman table optimization. Takes
longer, but results in smaller compressed
image. This only affects compression. |
'smooth' |
Perform inter-block smoothing on
uncompressed image. Only useful for low-
quality images. This only affects
decompression. |