recursive convolution for Gaussian smoothing and derivative kernels

include/vigra/kerneltraits.hxx

@@ -0,0 +1,100 @@
+//-- -*- c++ -*-
+/************************************************************************/
+/*                                                                      */
+/*               Copyright 2016 by Sven Peter and Ullrich Koethe        */
+/*                                                                      */
+/*    This file is part of the VIGRA computer vision library.           */
+/*    The VIGRA Website is                                              */
+/*        http://hci.iwr.uni-heidelberg.de/vigra/                       */
+/*    Please direct questions, bug reports, and contributions to        */
+/*        [email protected]    or                    */
+/*        [email protected]                               */
+/*                                                                      */
+/*    Permission is hereby granted, free of charge, to any person       */
+/*    obtaining a copy of this software and associated documentation    */
+/*    files (the "Software"), to deal in the Software without           */
+/*    restriction, including without limitation the rights to use,      */
+/*    copy, modify, merge, publish, distribute, sublicense, and/or      */
+/*    sell copies of the Software, and to permit persons to whom the    */
+/*    Software is furnished to do so, subject to the following          */
+/*    conditions:                                                       */
+/*                                                                      */
+/*    The above copyright notice and this permission notice shall be    */
+/*    included in all copies or substantial portions of the             */
+/*    Software.                                                         */
+/*                                                                      */
+/*    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND    */
+/*    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES   */
+/*    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND          */
+/*    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT       */
+/*    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,      */
+/*    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING      */
+/*    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR     */
+/*    OTHER DEALINGS IN THE SOFTWARE.                                   */
+/*                                                                      */
+/************************************************************************/
+
+#ifndef VIGRA_KERNEL_H
+#define VIGRA_KERNEL_H
+
+#include <type_traits>
+
+namespace vigra {
+namespace detail {
+
+struct fir_kernel1d_tag {};
+struct fir_kernel2d_tag {};
+struct iir_kernel1d_tag {};
+struct gaussian_kernel1d_tag {};
+
+template<typename X>
+struct is_kernel
+{
+	template <typename Y>
+	static char test(int, typename Y::vigra_kernel_category*);
+
+	template <typename Y>
+	static int test(int, ...);
+
+	static const bool value = (sizeof(char) == sizeof(test<X>(0,0)));
+};
+
+template<typename X, bool = is_kernel<X>::value >
+struct is_fir_kernel1d : public std::is_same<typename X::vigra_kernel_category, fir_kernel1d_tag>
+{
+};
+
+template<typename X, bool = is_kernel<X>::value >
+struct is_iir_kernel1d : public std::is_same<typename X::vigra_kernel_category, iir_kernel1d_tag>
+{
+};
+
+template<typename X, bool = is_kernel<X>::value >
+struct is_gaussian_kernel1d : public std::is_same<typename X::vigra_kernel_category, gaussian_kernel1d_tag>
+{
+};
+
+template<typename X>
+struct is_fir_kernel1d<X, false>
+{
+	static const bool value = false;
+};
+
+template<typename X>
+struct is_iir_kernel1d<X, false>
+{
+	static const bool value = false;
+};
+
+template<typename X>
+struct is_gaussian_kernel1d<X, false>
+{
+	static const bool value = false;
+};
+
+
+} // namespace detail
+
+} // namespace vigra
+
+#endif

include/vigra/mathutil.hxx

@@ -84,6 +84,10 @@
     #ifndef M_EULER_GAMMA
     #    define M_EULER_GAMMA  0.5772156649015329
     #endif
+
+    #ifndef M_SQRT2PI
+    #    define M_SQRT2PI 2.50662827463100050241576528481104525
+    #endif
     \endcode
 */
 #ifndef M_PI
@@ -114,6 +118,10 @@
 #    define M_EULER_GAMMA  0.5772156649015329
 #endif
 
+#ifndef M_SQRT2PI
+#    define M_SQRT2PI 2.50662827463100050241576528481104525
+#endif
+
 namespace vigra {
 
 /** \addtogroup MathFunctions Mathematical Functions