diff --git a/libs/image/vc_extra_math.h b/libs/image/vc_extra_math.h
index 42fbfa52ec..b02a26bb70 100644
--- a/libs/image/vc_extra_math.h
+++ b/libs/image/vc_extra_math.h
@@ -1,40 +1,58 @@
+/*
+ *  Copyright (c) 2018 Iván Santa María <ghevan@gmail.com>
+ *
+ *  This program 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 program 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 program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
 #ifndef VC_ADDITIONAL_MATH_H
 #define VC_ADDITIONAL_MATH_H
 
 #include <config-vc.h>
 
 #if defined HAVE_VC
 
 #include <Vc/Vc>
 #include <Vc/IO>
 
 class VcExtraMath
 {
 public:
     // vectorized erf function, precision 1e-5
     static inline Vc::float_v erf(Vc::float_v x) {
         Vc::float_v xa = abs(x);
         Vc::float_m precisionLimit(xa >= 9.3f); // wrong result for any number beyond this
         xa(precisionLimit) = 0;
         Vc::float_v sign(Vc::One);
         Vc::float_m invertMask = x < 0.f;
         sign(invertMask) = -1.f;
 
         // CONSTANTS
         float a1 =  0.254829592;
         float a2 = -0.284496736;
         float a3 =  1.421413741;
         float a4 = -1.453152027;
         float a5 =  1.061405429;
         float p  =  0.3275911;
 
         Vc::float_v t = 1.0f / (1.0f + p * xa);
         Vc::float_v y = 1.0f - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t * exp(-xa * xa);
         y(precisionLimit) = 1.0f;
         return sign * y;
     }
 };
 #endif /* defined HAVE_VC */
 
 
 #endif // VC_ADDITIONAL_MATH_H