jpeg — Read and write JPEG files
Platforms: IRIX
Deprecated since version 2.6: The jpeg module has been deprecated for removal in Python 3.0.
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. |
