| 1 | \section{\module{imgfile} ---
|
|---|
| 2 | Support for SGI imglib files}
|
|---|
| 3 |
|
|---|
| 4 | \declaremodule{builtin}{imgfile}
|
|---|
| 5 | \platform{IRIX}
|
|---|
| 6 | \modulesynopsis{Support for SGI imglib files.}
|
|---|
| 7 |
|
|---|
| 8 |
|
|---|
| 9 | The \module{imgfile} module allows Python programs to access SGI imglib image
|
|---|
| 10 | files (also known as \file{.rgb} files). The module is far from
|
|---|
| 11 | complete, but is provided anyway since the functionality that there is
|
|---|
| 12 | enough in some cases. Currently, colormap files are not supported.
|
|---|
| 13 |
|
|---|
| 14 | The module defines the following variables and functions:
|
|---|
| 15 |
|
|---|
| 16 | \begin{excdesc}{error}
|
|---|
| 17 | This exception is raised on all errors, such as unsupported file type, etc.
|
|---|
| 18 | \end{excdesc}
|
|---|
| 19 |
|
|---|
| 20 | \begin{funcdesc}{getsizes}{file}
|
|---|
| 21 | This function returns a tuple \code{(\var{x}, \var{y}, \var{z})} where
|
|---|
| 22 | \var{x} and \var{y} are the size of the image in pixels and
|
|---|
| 23 | \var{z} is the number of
|
|---|
| 24 | bytes per pixel. Only 3 byte RGB pixels and 1 byte greyscale pixels
|
|---|
| 25 | are currently supported.
|
|---|
| 26 | \end{funcdesc}
|
|---|
| 27 |
|
|---|
| 28 | \begin{funcdesc}{read}{file}
|
|---|
| 29 | This function reads and decodes the image on the specified file, and
|
|---|
| 30 | returns it as a Python string. The string has either 1 byte greyscale
|
|---|
| 31 | pixels or 4 byte RGBA pixels. The bottom left pixel is the first in
|
|---|
| 32 | the string. This format is suitable to pass to \function{gl.lrectwrite()},
|
|---|
| 33 | for instance.
|
|---|
| 34 | \end{funcdesc}
|
|---|
| 35 |
|
|---|
| 36 | \begin{funcdesc}{readscaled}{file, x, y, filter\optional{, blur}}
|
|---|
| 37 | This function is identical to read but it returns an image that is
|
|---|
| 38 | scaled to the given \var{x} and \var{y} sizes. If the \var{filter} and
|
|---|
| 39 | \var{blur} parameters are omitted scaling is done by
|
|---|
| 40 | simply dropping or duplicating pixels, so the result will be less than
|
|---|
| 41 | perfect, especially for computer-generated images.
|
|---|
| 42 |
|
|---|
| 43 | Alternatively, you can specify a filter to use to smooth the image
|
|---|
| 44 | after scaling. The filter forms supported are \code{'impulse'},
|
|---|
| 45 | \code{'box'}, \code{'triangle'}, \code{'quadratic'} and
|
|---|
| 46 | \code{'gaussian'}. If a filter is specified \var{blur} is an optional
|
|---|
| 47 | parameter specifying the blurriness of the filter. It defaults to \code{1.0}.
|
|---|
| 48 |
|
|---|
| 49 | \function{readscaled()} makes no attempt to keep the aspect ratio
|
|---|
| 50 | correct, so that is the users' responsibility.
|
|---|
| 51 | \end{funcdesc}
|
|---|
| 52 |
|
|---|
| 53 | \begin{funcdesc}{ttob}{flag}
|
|---|
| 54 | This function sets a global flag which defines whether the scan lines
|
|---|
| 55 | of the image are read or written from bottom to top (flag is zero,
|
|---|
| 56 | compatible with SGI GL) or from top to bottom(flag is one,
|
|---|
| 57 | compatible with X). The default is zero.
|
|---|
| 58 | \end{funcdesc}
|
|---|
| 59 |
|
|---|
| 60 | \begin{funcdesc}{write}{file, data, x, y, z}
|
|---|
| 61 | This function writes the RGB or greyscale data in \var{data} to image
|
|---|
| 62 | file \var{file}. \var{x} and \var{y} give the size of the image,
|
|---|
| 63 | \var{z} is 1 for 1 byte greyscale images or 3 for RGB images (which are
|
|---|
| 64 | stored as 4 byte values of which only the lower three bytes are used).
|
|---|
| 65 | These are the formats returned by \function{gl.lrectread()}.
|
|---|
| 66 | \end{funcdesc}
|
|---|
