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svn+ssh://pythondev@svn.python.org/python/trunk ........ r53545 | andrew.kuchling | 2007-01-24 21:06:41 +0100 (Wed, 24 Jan 2007) | 1 line Strengthen warning about using lock() ........ r53556 | thomas.heller | 2007-01-25 19:34:14 +0100 (Thu, 25 Jan 2007) | 3 lines Fix for #1643874: When calling SysAllocString, create a PyCObject which will eventually call SysFreeString to free the BSTR resource. ........ r53563 | andrew.kuchling | 2007-01-25 21:02:13 +0100 (Thu, 25 Jan 2007) | 1 line Add item ........ r53564 | brett.cannon | 2007-01-25 21:22:02 +0100 (Thu, 25 Jan 2007) | 8 lines Fix time.strptime's %U support. Basically rewrote the algorithm to be more generic so that one only has to shift certain values based on whether the week was specified to start on Monday or Sunday. Cut out a lot of edge case code compared to the previous version. Also broke algorithm out into its own function (that is private to the module). Fixes bug #1643943 (thanks Biran Nahas for the report). ........ r53570 | brett.cannon | 2007-01-26 00:30:39 +0100 (Fri, 26 Jan 2007) | 4 lines Remove specific mention of my name and email address from modules. Not really needed and all bug reports should go to the bug tracker, not directly to me. Plus I am not the only person to have edited these files at this point. ........ r53573 | fred.drake | 2007-01-26 17:28:44 +0100 (Fri, 26 Jan 2007) | 1 line fix typo (extraneous ")") ........ r53575 | georg.brandl | 2007-01-27 18:43:02 +0100 (Sat, 27 Jan 2007) | 4 lines Patch #1638243: the compiler package is now able to correctly compile a with statement; previously, executing code containing a with statement compiled by the compiler package crashed the interpreter. ........ r53578 | georg.brandl | 2007-01-27 18:59:42 +0100 (Sat, 27 Jan 2007) | 3 lines Patch #1634778: add missing encoding aliases for iso8859_15 and iso8859_16. ........ r53579 | georg.brandl | 2007-01-27 20:38:50 +0100 (Sat, 27 Jan 2007) | 2 lines Bug #1645944: os.access now returns bool but docstring is not updated ........ r53590 | brett.cannon | 2007-01-28 21:58:00 +0100 (Sun, 28 Jan 2007) | 2 lines Use the thread lock's context manager instead of a try/finally statement. ........ r53591 | brett.cannon | 2007-01-29 05:41:44 +0100 (Mon, 29 Jan 2007) | 2 lines Add a test for slicing an exception. ........ r53594 | andrew.kuchling | 2007-01-29 21:21:43 +0100 (Mon, 29 Jan 2007) | 1 line Minor edits to the curses HOWTO ........ r53596 | andrew.kuchling | 2007-01-29 21:55:40 +0100 (Mon, 29 Jan 2007) | 1 line Various minor edits ........ r53597 | andrew.kuchling | 2007-01-29 22:28:48 +0100 (Mon, 29 Jan 2007) | 1 line More edits ........ r53601 | tim.peters | 2007-01-30 04:03:46 +0100 (Tue, 30 Jan 2007) | 2 lines Whitespace normalization. ........ r53603 | georg.brandl | 2007-01-30 21:21:30 +0100 (Tue, 30 Jan 2007) | 2 lines Bug #1648191: typo in docs. ........ r53605 | brett.cannon | 2007-01-30 22:34:36 +0100 (Tue, 30 Jan 2007) | 8 lines No more raising of string exceptions! The next step of PEP 352 (for 2.6) causes raising a string exception to trigger a TypeError. Trying to catch a string exception raises a DeprecationWarning. References to string exceptions has been removed from the docs since they are now just an error. ........ r53618 | raymond.hettinger | 2007-02-01 22:02:59 +0100 (Thu, 01 Feb 2007) | 1 line Bug #1648179: set.update() not recognizing __iter__ overrides in dict subclasses. ........
100 lines
4 KiB
TeX
100 lines
4 KiB
TeX
\section{\module{imageop} ---
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Manipulate raw image data}
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\declaremodule{builtin}{imageop}
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\modulesynopsis{Manipulate raw image data.}
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The \module{imageop} module contains some useful operations on images.
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It operates on images consisting of 8 or 32 bit pixels stored in
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Python strings. This is the same format as used by
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\function{gl.lrectwrite()} and the \refmodule{imgfile} module.
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The module defines the following variables and functions:
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\begin{excdesc}{error}
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This exception is raised on all errors, such as unknown number of bits
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per pixel, etc.
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\end{excdesc}
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\begin{funcdesc}{crop}{image, psize, width, height, x0, y0, x1, y1}
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Return the selected part of \var{image}, which should be
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\var{width} by \var{height} in size and consist of pixels of
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\var{psize} bytes. \var{x0}, \var{y0}, \var{x1} and \var{y1} are like
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the \function{gl.lrectread()} parameters, i.e.\ the boundary is
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included in the new image. The new boundaries need not be inside the
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picture. Pixels that fall outside the old image will have their value
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set to zero. If \var{x0} is bigger than \var{x1} the new image is
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mirrored. The same holds for the y coordinates.
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\end{funcdesc}
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\begin{funcdesc}{scale}{image, psize, width, height, newwidth, newheight}
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Return \var{image} scaled to size \var{newwidth} by \var{newheight}.
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No interpolation is done, scaling is done by simple-minded pixel
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duplication or removal. Therefore, computer-generated images or
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dithered images will not look nice after scaling.
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\end{funcdesc}
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\begin{funcdesc}{tovideo}{image, psize, width, height}
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Run a vertical low-pass filter over an image. It does so by computing
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each destination pixel as the average of two vertically-aligned source
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pixels. The main use of this routine is to forestall excessive
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flicker if the image is displayed on a video device that uses
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interlacing, hence the name.
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\end{funcdesc}
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\begin{funcdesc}{grey2mono}{image, width, height, threshold}
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Convert a 8-bit deep greyscale image to a 1-bit deep image by
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thresholding all the pixels. The resulting image is tightly packed and
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is probably only useful as an argument to \function{mono2grey()}.
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\end{funcdesc}
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\begin{funcdesc}{dither2mono}{image, width, height}
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Convert an 8-bit greyscale image to a 1-bit monochrome image using a
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(simple-minded) dithering algorithm.
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\end{funcdesc}
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\begin{funcdesc}{mono2grey}{image, width, height, p0, p1}
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Convert a 1-bit monochrome image to an 8 bit greyscale or color image.
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All pixels that are zero-valued on input get value \var{p0} on output
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and all one-value input pixels get value \var{p1} on output. To
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convert a monochrome black-and-white image to greyscale pass the
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values \code{0} and \code{255} respectively.
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\end{funcdesc}
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\begin{funcdesc}{grey2grey4}{image, width, height}
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Convert an 8-bit greyscale image to a 4-bit greyscale image without
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dithering.
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\end{funcdesc}
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\begin{funcdesc}{grey2grey2}{image, width, height}
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Convert an 8-bit greyscale image to a 2-bit greyscale image without
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dithering.
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\end{funcdesc}
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\begin{funcdesc}{dither2grey2}{image, width, height}
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Convert an 8-bit greyscale image to a 2-bit greyscale image with
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dithering. As for \function{dither2mono()}, the dithering algorithm
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is currently very simple.
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\end{funcdesc}
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\begin{funcdesc}{grey42grey}{image, width, height}
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Convert a 4-bit greyscale image to an 8-bit greyscale image.
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\end{funcdesc}
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\begin{funcdesc}{grey22grey}{image, width, height}
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Convert a 2-bit greyscale image to an 8-bit greyscale image.
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\end{funcdesc}
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\begin{datadesc}{backward_compatible}
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If set to 0, the functions in this module use a non-backward
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compatible way of representing multi-byte pixels on little-endian
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systems. The SGI for which this module was originally written is a
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big-endian system, so setting this variable will have no effect.
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However, the code wasn't originally intended to run on anything else,
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so it made assumptions about byte order which are not universal.
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Setting this variable to 0 will cause the byte order to be reversed on
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little-endian systems, so that it then is the same as on big-endian
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systems.
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\end{datadesc}
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