From 9dc23db287bf61d65744561320231d1fe611fc06 Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <pavel@cs.unc.edu>
Date: Tue, 18 Feb 2014 13:25:29 -0500
Subject: [PATCH] Add YCoCg pixel type

---
 Base/include/Pixel.h | 24 +++++++++++++++++++++++-
 Base/src/Pixel.cpp   | 31 +++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/Base/include/Pixel.h b/Base/include/Pixel.h
index 31833b9..2f02b64 100644
--- a/Base/include/Pixel.h
+++ b/Base/include/Pixel.h
@@ -59,7 +59,7 @@
 namespace FasTC {
 
 class Pixel : public Vector4<uint16> {
- private:
+ protected:
   typedef uint16 ChannelType;
   typedef Vector4<ChannelType> VectorType;
   uint8 m_BitDepth[4];
@@ -159,6 +159,28 @@ class Pixel : public Vector4<uint16> {
 };
 REGISTER_VECTOR_TYPE(Pixel);
 
+class YCoCgPixel : public Pixel {
+ private:
+  void ToYCoCg();
+
+ public:
+  YCoCgPixel() : Pixel() { }
+  explicit YCoCgPixel(uint32 rgba) : Pixel(rgba) { ToYCoCg(); }
+  explicit YCoCgPixel(const Pixel &p) : Pixel(p) { ToYCoCg(); }
+
+  Pixel ToRGBA() const;
+
+  float ToIntensity() const { return ConvertChannelToFloat(R(), 8); }
+  uint32 Pack() const { return ToRGBA().Pack(); }
+  void Unpack(uint32 rgba) { Pixel::Unpack(rgba); ToYCoCg(); }
+
+  const ChannelType &Co() const { return Z(); }
+  ChannelType &Co() { return Z(); }
+  const ChannelType &Cg() const { return W(); }
+  ChannelType &Cg() { return W(); }  
+};
+REGISTER_VECTOR_TYPE(YCoCgPixel);
+
 }  // namespace FasTC
 
 #endif  // BASE_INCLUDE_PIXEL_H_
diff --git a/Base/src/Pixel.cpp b/Base/src/Pixel.cpp
index 8364dd2..7806292 100644
--- a/Base/src/Pixel.cpp
+++ b/Base/src/Pixel.cpp
@@ -56,6 +56,11 @@
 #include <cassert>
 #include <algorithm>
 
+template<typename T>
+static inline T Clamp(const T &v, const T &_min, const T &_max) {
+  return std::max(_min, std::min(v, _max));
+}
+
 namespace FasTC {
 
   void Pixel::FromBits(const uint8 *bits,
@@ -260,4 +265,30 @@ namespace FasTC {
     return ok;
   }
 
+  void YCoCgPixel::ToYCoCg() {
+    int16 Y = ((R() + (G() << 1) + B()) + 2) >> 2;
+    int16 Co = (R() - B() + 1) >> 1;
+    int16 Cg = ((-R() + (G() << 1) - B()) + 2) >> 2;
+
+    this->Y() = Clamp<int16>(Y, 0, 255);
+    this->Co() = Clamp<int16>(Co + 128, 0, 255);
+    this->Cg() = Clamp<int16>(Cg + 128, 0, 255);
+  }
+
+  Pixel YCoCgPixel::ToRGBA() const {
+    int16 Co = this->Co() - 128;
+    int16 Cg = this->Cg() - 128;
+
+    int16 R = Y() + (Co - Cg);
+    int16 G = Y() + Cg;
+    int16 B = Y() - (Co + Cg);
+
+    Pixel p;
+    p.R() = Clamp<int16>(R, 0, 255);
+    p.G() = Clamp<int16>(G, 0, 255);
+    p.B() = Clamp<int16>(B, 0, 255);
+    p.A() = A();
+    return p;
+  }
+
 }  // namespace FasTC