69 lines
2.6 KiB
ReStructuredText
69 lines
2.6 KiB
ReStructuredText
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:mod:`imgfile` --- Support for SGI imglib files
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===============================================
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.. module:: imgfile
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:platform: IRIX
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:synopsis: Support for SGI imglib files.
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The :mod:`imgfile` module allows Python programs to access SGI imglib image
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files (also known as :file:`.rgb` files). The module is far from complete, but
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is provided anyway since the functionality that there is enough in some cases.
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Currently, colormap files are not supported.
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The module defines the following variables and functions:
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.. exception:: error
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This exception is raised on all errors, such as unsupported file type, etc.
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.. function:: getsizes(file)
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This function returns a tuple ``(x, y, z)`` where *x* and *y* are the size of
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the image in pixels and *z* is the number of bytes per pixel. Only 3 byte RGB
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pixels and 1 byte greyscale pixels are currently supported.
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.. function:: read(file)
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This function reads and decodes the image on the specified file, and returns it
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as a Python string. The string has either 1 byte greyscale pixels or 4 byte RGBA
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pixels. The bottom left pixel is the first in the string. This format is
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suitable to pass to :func:`gl.lrectwrite`, for instance.
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.. function:: readscaled(file, x, y, filter[, blur])
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This function is identical to read but it returns an image that is scaled to the
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given *x* and *y* sizes. If the *filter* and *blur* parameters are omitted
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scaling is done by simply dropping or duplicating pixels, so the result will be
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less than perfect, especially for computer-generated images.
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Alternatively, you can specify a filter to use to smooth the image after
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scaling. The filter forms supported are ``'impulse'``, ``'box'``,
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``'triangle'``, ``'quadratic'`` and ``'gaussian'``. If a filter is specified
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*blur* is an optional parameter specifying the blurriness of the filter. It
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defaults to ``1.0``.
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:func:`readscaled` makes no attempt to keep the aspect ratio correct, so that is
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the users' responsibility.
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.. function:: ttob(flag)
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This function sets a global flag which defines whether the scan lines of the
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image are read or written from bottom to top (flag is zero, compatible with SGI
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GL) or from top to bottom(flag is one, compatible with X). The default is zero.
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.. function:: write(file, data, x, y, z)
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This function writes the RGB or greyscale data in *data* to image file *file*.
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*x* and *y* give the size of the image, *z* is 1 for 1 byte greyscale images or
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3 for RGB images (which are stored as 4 byte values of which only the lower
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three bytes are used). These are the formats returned by :func:`gl.lrectread`.
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