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| 55 | <H1><A NAME="SECTION00221100000000000000000"> |
| 56 | 20.11 <tt class="module">imgfile</tt> -- |
| 57 | Support for SGI imglib files</A> |
| 58 | </H1> |
| 59 | |
| 60 | <P> |
| 61 | <A NAME="module-imgfile"></A> |
| 62 | <p class="availability">Availability: <span |
| 63 | class="platform">IRIX</span>.</p> |
| 64 | |
| 65 | <P> |
| 66 | The <tt class="module">imgfile</tt> module allows Python programs to access SGI imglib image |
| 67 | files (also known as <span class="file">.rgb</span> files). The module is far from |
| 68 | complete, but is provided anyway since the functionality that there is |
| 69 | enough in some cases. Currently, colormap files are not supported. |
| 70 | |
| 71 | <P> |
| 72 | The module defines the following variables and functions: |
| 73 | |
| 74 | <P> |
| 75 | <dl><dt><b><span class="typelabel">exception</span> <tt id='l2h-5207' xml:id='l2h-5207' class="exception">error</tt></b></dt> |
| 76 | <dd> |
| 77 | This exception is raised on all errors, such as unsupported file type, etc. |
| 78 | </dd></dl> |
| 79 | |
| 80 | <P> |
| 81 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 82 | <td><nobr><b><tt id='l2h-5208' xml:id='l2h-5208' class="function">getsizes</tt></b>(</nobr></td> |
| 83 | <td><var>file</var>)</td></tr></table></dt> |
| 84 | <dd> |
| 85 | This function returns a tuple <code>(<var>x</var>, <var>y</var>, <var>z</var>)</code> where |
| 86 | <var>x</var> and <var>y</var> are the size of the image in pixels and |
| 87 | <var>z</var> is the number of |
| 88 | bytes per pixel. Only 3 byte RGB pixels and 1 byte greyscale pixels |
| 89 | are currently supported. |
| 90 | </dl> |
| 91 | |
| 92 | <P> |
| 93 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 94 | <td><nobr><b><tt id='l2h-5209' xml:id='l2h-5209' class="function">read</tt></b>(</nobr></td> |
| 95 | <td><var>file</var>)</td></tr></table></dt> |
| 96 | <dd> |
| 97 | This function reads and decodes the image on the specified file, and |
| 98 | returns it as a Python string. The string has either 1 byte greyscale |
| 99 | pixels or 4 byte RGBA pixels. The bottom left pixel is the first in |
| 100 | the string. This format is suitable to pass to <tt class="function">gl.lrectwrite()</tt>, |
| 101 | for instance. |
| 102 | </dl> |
| 103 | |
| 104 | <P> |
| 105 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 106 | <td><nobr><b><tt id='l2h-5210' xml:id='l2h-5210' class="function">readscaled</tt></b>(</nobr></td> |
| 107 | <td><var>file, x, y, filter</var><big>[</big><var>, blur</var><big>]</big><var></var>)</td></tr></table></dt> |
| 108 | <dd> |
| 109 | This function is identical to read but it returns an image that is |
| 110 | scaled to the given <var>x</var> and <var>y</var> sizes. If the <var>filter</var> and |
| 111 | <var>blur</var> parameters are omitted scaling is done by |
| 112 | simply dropping or duplicating pixels, so the result will be less than |
| 113 | perfect, especially for computer-generated images. |
| 114 | |
| 115 | <P> |
| 116 | Alternatively, you can specify a filter to use to smooth the image |
| 117 | after scaling. The filter forms supported are <code>'impulse'</code>, |
| 118 | <code>'box'</code>, <code>'triangle'</code>, <code>'quadratic'</code> and |
| 119 | <code>'gaussian'</code>. If a filter is specified <var>blur</var> is an optional |
| 120 | parameter specifying the blurriness of the filter. It defaults to <code>1.0</code>. |
| 121 | |
| 122 | <P> |
| 123 | <tt class="function">readscaled()</tt> makes no attempt to keep the aspect ratio |
| 124 | correct, so that is the users' responsibility. |
| 125 | </dl> |
| 126 | |
| 127 | <P> |
| 128 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 129 | <td><nobr><b><tt id='l2h-5211' xml:id='l2h-5211' class="function">ttob</tt></b>(</nobr></td> |
| 130 | <td><var>flag</var>)</td></tr></table></dt> |
| 131 | <dd> |
| 132 | This function sets a global flag which defines whether the scan lines |
| 133 | of the image are read or written from bottom to top (flag is zero, |
| 134 | compatible with SGI GL) or from top to bottom(flag is one, |
| 135 | compatible with X). The default is zero. |
| 136 | </dl> |
| 137 | |
| 138 | <P> |
| 139 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 140 | <td><nobr><b><tt id='l2h-5212' xml:id='l2h-5212' class="function">write</tt></b>(</nobr></td> |
| 141 | <td><var>file, data, x, y, z</var>)</td></tr></table></dt> |
| 142 | <dd> |
| 143 | This function writes the RGB or greyscale data in <var>data</var> to image |
| 144 | file <var>file</var>. <var>x</var> and <var>y</var> give the size of the image, |
| 145 | <var>z</var> is 1 for 1 byte greyscale images or 3 for RGB images (which are |
| 146 | stored as 4 byte values of which only the lower three bytes are used). |
| 147 | These are the formats returned by <tt class="function">gl.lrectread()</tt>. |
| 148 | </dl> |
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