39.11. "imgfile" — Support for SGI imglib files
***********************************************

Obsoleto desde a versão 2.6: The "imgfile" module has been removed in
Python 3.

The "imgfile" module allows Python programs to access SGI imglib image
files (also known as ".rgb" files).  The module is far from complete,
but is provided anyway since the functionality that there is enough in
some cases. Currently, colormap files are not supported.

The module defines the following variables and functions:

exception imgfile.error

   This exception is raised on all errors, such as unsupported file
   type, etc.

imgfile.getsizes(file)

   This function returns a tuple "(x, y, z)" where *x* and *y* are the
   size of the image in pixels and *z* is the number of bytes per
   pixel. Only 3 byte RGB pixels and 1 byte greyscale pixels are
   currently supported.

imgfile.read(file)

   This function reads and decodes the image on the specified file,
   and returns it as a Python string. The string has either 1 byte
   greyscale pixels or 4 byte RGBA pixels. The bottom left pixel is
   the first in the string. This format is suitable to pass to
   "gl.lrectwrite()", for instance.

imgfile.readscaled(file, x, y, filter[, blur])

   This function is identical to read but it returns an image that is
   scaled to the given *x* and *y* sizes. If the *filter* and *blur*
   parameters are omitted scaling is done by simply dropping or
   duplicating pixels, so the result will be less than perfect,
   especially for computer-generated images.

   Alternatively, you can specify a filter to use to smooth the image
   after scaling. The filter forms supported are "'impulse'", "'box'",
   "'triangle'", "'quadratic'" and "'gaussian'". If a filter is
   specified *blur* is an optional parameter specifying the blurriness
   of the filter. It defaults to "1.0".

   "readscaled()" makes no attempt to keep the aspect ratio correct,
   so that is the users’ responsibility.

imgfile.ttob(flag)

   This function sets a global flag which defines whether the scan
   lines of the image are read or written from bottom to top (flag is
   zero, compatible with SGI GL) or from top to bottom(flag is one,
   compatible with X).  The default is zero.

imgfile.write(file, data, x, y, z)

   This function writes the RGB or greyscale data in *data* to image
   file *file*. *x* and *y* give the size of the image, *z* is 1 for 1
   byte greyscale images or 3 for RGB images (which are stored as 4
   byte values of which only the lower three bytes are used). These
   are the formats returned by "gl.lrectread()".
