93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
// code by HJ Hornbeck, based on code copyright David Hilvert
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/* This file is part of the Anti-Lamenessing Engine.
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The Anti-Lamenessing Engine is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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The Anti-Lamenessing Engine is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with the Anti-Lamenessing Engine; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef __d2_filter_gauss_h__
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#define __d2_filter_gauss_h__
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/*
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* A Gaussian filter.
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*/
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class gauss : public filter {
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private:
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ale_pos sigma;
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ale_pos diameter; /** measured in standard deviations **/
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/*
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* The heavy-lifting function:
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*/
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ale_real _calc(ale_pos p) const {
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/** catch the trivial cases **/
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if ( p == 0 ) return 1;
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/** if ( p > (sigma*diameter) ) return 0;
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^^ unnecessary, gauss is well-behaved
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outside its radius **/
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/** calculate the rest **/
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ale_pos p2 = p * p;
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ale_pos sigma2 = sigma * sigma;
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return exp( -(p2/sigma2) );
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}
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/** extend the heavy-lifting function to handle a coordinate **/
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ale_real _calc(point p) const {
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return _calc( sqrt( (p[0]*p[0]) + (p[1]*p[1]) ) );
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/** doesn't work as well:
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return _calc( p[0] ) * _calc( p[1] ); **/
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}
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public:
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/*
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* Size of filter support, or how big a radius does this filter
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* touch?
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*/
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ale_pos support() const {
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return sigma*diameter;
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}
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/*
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* Response of filter at point p
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*/
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virtual ale_real response(point p) const {
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return _calc(p);
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}
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/** only compare standard deviations, since this version fixes
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the diameter across all instances **/
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virtual int equals(const filter *f) const {
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if (typeid(*f) == typeid(*this))
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return ((gauss *)f)->sigma == sigma;
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return 0;
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}
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gauss(ale_pos sigma) {
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this->sigma = sigma;
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this->diameter = 2; /** fixed, standard for imaging **/
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}
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};
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#endif
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