diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/lib/libjpeg.tex | 79 | ||||
| -rw-r--r-- | Doc/libjpeg.tex | 79 |
2 files changed, 84 insertions, 74 deletions
diff --git a/Doc/lib/libjpeg.tex b/Doc/lib/libjpeg.tex index 75691cf..745fe32 100644 --- a/Doc/lib/libjpeg.tex +++ b/Doc/lib/libjpeg.tex @@ -2,51 +2,56 @@ \label{module-jpeg} \bimodindex{jpeg} -The module \code{jpeg} provides access to the jpeg compressor and -decompressor written by the Independent JPEG Group. JPEG is a (draft?)\ +The module \module{jpeg} provides access to the jpeg compressor and +decompressor written by the Independent JPEG Group. JPEG is a (draft?) standard for compressing pictures. For details on jpeg or the Independent JPEG Group software refer to the JPEG standard or the documentation provided with the software. -The \code{jpeg} module defines these functions: - -\setindexsubitem{(in module jpeg)} -\begin{funcdesc}{compress}{data\, w\, h\, b} -Treat data as a pixmap of width \var{w} and height \var{h}, with \var{b} bytes per -pixel. The data is in SGI GL order, so the first pixel is in the -lower-left corner. This means that \code{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. +The \module{jpeg} module defines an exception and some functions. + +\begin{excdesc}{error} +Exception raised by \function{compress()} and \function{decompress()} +in case of errors. +\end{excdesc} + +\begin{funcdesc}{compress}{data, w, h, b} +Treat data as a pixmap of width \var{w} and height \var{h}, with +\var{b} bytes per pixel. The data is in SGI GL order, so the first +pixel is in the lower-left corner. This means that \code{gl.lrectread} +return data can immediately be passed to \function{compress()}. +Currently only 1 byte and 4 byte pixels are allowed, the former being +treated as greyscale and the latter as RGB color. +\function{compress()} returns a string that contains the compressed +picture, in JFIF format. \end{funcdesc} \begin{funcdesc}{decompress}{data} Data is a string containing a picture in JFIF format. It returns a -tuple -\code{(\var{data}, \var{width}, \var{height}, \var{bytesperpixel})}. -Again, the data is suitable to pass to \code{lrectwrite}. +tuple \code{(\var{data}, \var{width}, \var{height}, +\var{bytesperpixel})}. Again, the data is suitable to pass to +\code{gl.lrectwrite}. \end{funcdesc} -\begin{funcdesc}{setoption}{name\, value} -Set various options. Subsequent compress and decompress calls -will use these options. The following options are available: -\begin{description} -\item[\code{'forcegray' }] -Force output to be grayscale, even if input is RGB. - -\item[\code{'quality' }] -Set the quality of the compressed image to a -value between \code{0} and \code{100} (default is \code{75}). Compress only. - -\item[\code{'optimize' }] -Perform Huffman table optimization. Takes longer, but results in -smaller compressed image. Compress only. - -\item[\code{'smooth' }] -Perform inter-block smoothing on uncompressed image. Only useful for -low-quality images. Decompress only. -\end{description} +\begin{funcdesc}{setoption}{name, value} +Set various options. Subsequent \function{compress()} and +\function{decompress()} calls will use these options. The following +options are available: + +\begin{tableii}{|l|l|}{code}{Option}{Effect} + \lineii{'forcegray'}{% + Force output to be grayscale, even if input is RGB.} + \lineii{'quality'}{% + Set the quality of the compressed image to a value between + \code{0} and \code{100} (default is \code{75}). \\ + &This only affects compression.} + \lineii{'optimize'}{% + Perform Huffman table optimization. Takes longer, but results in + smaller compressed \\ + &image. This only affects compression.} + \lineii{'smooth'}{% + Perform inter-block smoothing on uncompressed image. Only useful + for low-quality \\ + &images. This only affects decompression.} +\end{tableii} \end{funcdesc} - -Compress and uncompress raise the error \code{jpeg.error} in case of errors. diff --git a/Doc/libjpeg.tex b/Doc/libjpeg.tex index 75691cf..745fe32 100644 --- a/Doc/libjpeg.tex +++ b/Doc/libjpeg.tex @@ -2,51 +2,56 @@ \label{module-jpeg} \bimodindex{jpeg} -The module \code{jpeg} provides access to the jpeg compressor and -decompressor written by the Independent JPEG Group. JPEG is a (draft?)\ +The module \module{jpeg} provides access to the jpeg compressor and +decompressor written by the Independent JPEG Group. JPEG is a (draft?) standard for compressing pictures. For details on jpeg or the Independent JPEG Group software refer to the JPEG standard or the documentation provided with the software. -The \code{jpeg} module defines these functions: - -\setindexsubitem{(in module jpeg)} -\begin{funcdesc}{compress}{data\, w\, h\, b} -Treat data as a pixmap of width \var{w} and height \var{h}, with \var{b} bytes per -pixel. The data is in SGI GL order, so the first pixel is in the -lower-left corner. This means that \code{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. +The \module{jpeg} module defines an exception and some functions. + +\begin{excdesc}{error} +Exception raised by \function{compress()} and \function{decompress()} +in case of errors. +\end{excdesc} + +\begin{funcdesc}{compress}{data, w, h, b} +Treat data as a pixmap of width \var{w} and height \var{h}, with +\var{b} bytes per pixel. The data is in SGI GL order, so the first +pixel is in the lower-left corner. This means that \code{gl.lrectread} +return data can immediately be passed to \function{compress()}. +Currently only 1 byte and 4 byte pixels are allowed, the former being +treated as greyscale and the latter as RGB color. +\function{compress()} returns a string that contains the compressed +picture, in JFIF format. \end{funcdesc} \begin{funcdesc}{decompress}{data} Data is a string containing a picture in JFIF format. It returns a -tuple -\code{(\var{data}, \var{width}, \var{height}, \var{bytesperpixel})}. -Again, the data is suitable to pass to \code{lrectwrite}. +tuple \code{(\var{data}, \var{width}, \var{height}, +\var{bytesperpixel})}. Again, the data is suitable to pass to +\code{gl.lrectwrite}. \end{funcdesc} -\begin{funcdesc}{setoption}{name\, value} -Set various options. Subsequent compress and decompress calls -will use these options. The following options are available: -\begin{description} -\item[\code{'forcegray' }] -Force output to be grayscale, even if input is RGB. - -\item[\code{'quality' }] -Set the quality of the compressed image to a -value between \code{0} and \code{100} (default is \code{75}). Compress only. - -\item[\code{'optimize' }] -Perform Huffman table optimization. Takes longer, but results in -smaller compressed image. Compress only. - -\item[\code{'smooth' }] -Perform inter-block smoothing on uncompressed image. Only useful for -low-quality images. Decompress only. -\end{description} +\begin{funcdesc}{setoption}{name, value} +Set various options. Subsequent \function{compress()} and +\function{decompress()} calls will use these options. The following +options are available: + +\begin{tableii}{|l|l|}{code}{Option}{Effect} + \lineii{'forcegray'}{% + Force output to be grayscale, even if input is RGB.} + \lineii{'quality'}{% + Set the quality of the compressed image to a value between + \code{0} and \code{100} (default is \code{75}). \\ + &This only affects compression.} + \lineii{'optimize'}{% + Perform Huffman table optimization. Takes longer, but results in + smaller compressed \\ + &image. This only affects compression.} + \lineii{'smooth'}{% + Perform inter-block smoothing on uncompressed image. Only useful + for low-quality \\ + &images. This only affects decompression.} +\end{tableii} \end{funcdesc} - -Compress and uncompress raise the error \code{jpeg.error} in case of errors. |