92 lines
3.0 KiB
HTML
92 lines
3.0 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<title>ALE User Manual: Point Spread Functions</title>
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<table align=right valign=top width=160>
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<td valign=top height=600 width=160>
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<a href="http://auricle.dyndns.org/ALE/">
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<big>ALE</big>
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<br>
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Image Processing Software
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<br>
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<br>
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<small>Deblurring, Anti-aliasing, and Superresolution.</small></a>
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<br><br>
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<big>
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Local Operation
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</big>
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<hr>
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localhost<br>
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2684415918<br>
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<p><b>[ <a href="../">Up</a> ]</b></p>
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<h1>ALE Point Spread Functions</h1>
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<p>The ALE Irani-Peleg renderer uses a point-spread function to model the optical
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and electronic properties of the capture device used. The PSF can be specified
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in terms of one linear and one non-linear component.
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<h3>PSF specification</h3>
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<p>The PSF can be explicitly specified by using one or both of the psf options.
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<pre>
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--lpsf <p> Set linear colorspace point-spread function to <p>
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--nlpsf <p> Set non-linear colorspace point-spread function to <p>
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</pre>
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Available explicit point-spread functions are as follows:
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<pre>
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box=<d> Set the PSF to a box filter with diameter <d>.
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circle=<d> Set the PSF to a circular filter with diameter <d>.
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stdin Specify a custom filter at runtime.
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stdin_vg stdin with vertically-oriented gaps after every 8th pixel.
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<p>+<p> Summation of two functions
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<p>^<p> Convolution of two functions.
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<n>*<p> Multiplication by a scalar <n>.
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</pre>
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If a device is known to ALE, then its PSF can be implicitly set with the
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<code>--device</code> option. (See the <a href="../../device/">device</a> page
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for more information.) If a device is not specified, then the default linear
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PSF component is <code>box=1</code>. The non-linear PSF component is disabled
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by default.
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<h3>Determining the PSF</h3>
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<p>The PSF can be approximated based on images of known scenes. The ALE source
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distribution includes an experimental script that numerically approximates the
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PSF in this way (<code>d2/render/psf/ale-psf-calibrate</code>). Other, more
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efficient methods for approximating the PSF are likely possible, however.
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<br>
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<hr>
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<i>Copyright 2003, 2004 <a href="mailto:dhilvert@auricle.dyndns.org">David Hilvert</a></i>
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<p>Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.
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</body>
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