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@ -41,10 +41,10 @@ example, let’s display the image we just loaded::
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.. note::
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The standard version of :py:meth:`~PIL.Image.Image.show` is not very
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efficient, since it saves the image to a temporary file and calls the
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:command:`xv` utility to display the image. If you don’t have :command:`xv`
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installed, it won’t even work. When it does work though, it is very handy
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for debugging and tests.
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efficient, since it saves the image to a temporary file and calls a utility
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to display the image. If you don’t have an appropriate utility installed,
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it won’t even work. When it does work though, it is very handy for
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debugging and tests.
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The following sections provide an overview of the different functions provided in this library.
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@ -183,20 +183,11 @@ Rolling an image
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part1 = image.crop((0, 0, delta, ysize))
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part2 = image.crop((delta, 0, xsize, ysize))
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part1.load()
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part2.load()
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image.paste(part2, (0, 0, xsize-delta, ysize))
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image.paste(part1, (xsize-delta, 0, xsize, ysize))
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image.paste(part2, (0, 0, xsize-delta, ysize))
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return image
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Note that when pasting it back from the :py:meth:`~PIL.Image.Image.crop`
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operation, :py:meth:`~PIL.Image.Image.load` is called first. This is because
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cropping is a lazy operation. If :py:meth:`~PIL.Image.Image.load` was not
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called, then the crop operation would not be performed until the images were
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used in the paste commands. This would mean that ``part1`` would be cropped from
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the version of ``image`` already modified by the first paste.
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For more advanced tricks, the paste method can also take a transparency mask as
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an optional argument. In this mask, the value 255 indicates that the pasted
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image is opaque in that position (that is, the pasted image should be used as
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