From bf5429cd0c9e7f5f0bc4903de33d54e20d4ce8b7 Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <pavel@cs.unc.edu>
Date: Thu, 10 Oct 2013 20:06:12 -0400
Subject: [PATCH] Add Gaussian kernel generating function.

---
 Base/include/Image.h |  2 ++
 Base/src/Image.cpp   | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/Base/include/Image.h b/Base/include/Image.h
index ddd0428..1c70712 100644
--- a/Base/include/Image.h
+++ b/Base/include/Image.h
@@ -125,6 +125,8 @@ namespace FasTC {
     void ConvertFromBlockStreamOrder();
   };
 
+  extern void GenerateGaussianKernel(Image<IPixel> &out, uint32 size, float sigma);
+
 }  // namespace FasTC
 
 #endif // __TEXCOMP_IMAGE_H__
diff --git a/Base/src/Image.cpp b/Base/src/Image.cpp
index 1e8561c..dcff088 100644
--- a/Base/src/Image.cpp
+++ b/Base/src/Image.cpp
@@ -350,4 +350,22 @@ template class Image<Pixel>;
 template class Image<IPixel>;
 template class Image<Color>;
 
+void GenerateGaussianKernel(Image<IPixel> &out, uint32 size, float sigma) {
+
+  assert(size % 2);
+
+  out = Image<IPixel>(size, size);
+  if(size == 1) {
+    out(0, 0) = 1.0f;
+    return;
+  }
+
+  int32 halfSz = static_cast<int32>(size) / 2;
+  for(int32 j = -halfSz; j < halfSz; j++) {
+    for(int32 i = -halfSz; i < halfSz; i++) {
+      out(i, j) = exp(- (j*j + i*i) / (2*sigma*sigma));
+    }
+  }
+}
+
 }  // namespace FasTC