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Availability: IRIX.
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 error
-
Exception raised by compress() and decompress()
in case of errors.
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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.
-
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().
-
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. |
Release 2.5.2, documentation updated on 21th February, 2008.
See About this document... for information on suggesting changes.
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