/usr/share/aqsis/shaders/imager/filmgrain.sl is in aqsis 1.8.2-10.
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// Copyright 1997 - 2001, Paul C. Gregory
//
// Contact: pgregory@aqsis.org
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
/** \file
\brief An imager shader to create film grain
\author Tristan Colgate-McFarlane (tristan@cream.org)
*/
imager filmgrain ()
{
// We only apply the grain to the mid range of the image, bright and dark areas don't
// get much.
color CiHSV = ctransform("hsv",Ci);
float CiV = comp(CiHSV,2);
float MidV = sin (CiV * PI) / 4;
float grain = float noise (s,t);
Ci = Ci * (1 - ( MidV * grain ) );
Oi = 1;
alpha = 1;
}
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