Deprecated since version 2.6: The jpeg module has been removed in Python 3.
模块 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 raised by compress() and decompress() in case of errors.
Treat data as a pixmap of width w and height h ，采用 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:
| 选项 | 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 (默认 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. |
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