[x265] [PATCH] primitives :added C primitives to compute SSIM

[Aarthi Thirumalai]

# HG changeset patch
# User Aarthi Thirumalai
# Date 1380629233 -19800
#      Tue Oct 01 17:37:13 2013 +0530
# Node ID bc38d51440330519f411e46d34cf176e7b728069
# Parent  fc225ea42650867a229d15f41e1f2a495629bb7d
primitives :added C primitives to compute SSIM
ssim_4x4x2_core_hb( for high bit depth enabled) , ssim_4x4x2_core_lb(for high bit depth disabled)

diff -r fc225ea42650 -r bc38d5144033 source/common/pixel.cpp
--- a/source/common/pixel.cpp	Tue Oct 01 17:28:19 2013 +0530
+++ b/source/common/pixel.cpp	Tue Oct 01 17:37:13 2013 +0530
@@ -636,6 +636,69 @@
     }
 }
 
+ /* structural similarity metric */
+template<class T1>
+void ssim_4x4x2_core(const pixel *pix1, intptr_t stride1, const pixel *pix2, intptr_t stride2, T1 sums[2][4])
+{
+    for (int z = 0; z < 2; z++)
+    {
+        T1 s1 = 0, s2 = 0, ss = 0, s12 = 0;
+        for (int y = 0; y < 4; y++)
+            for (int x = 0; x < 4; x++)
+            {
+                int a = pix1[x + y * stride1];
+                int b = pix2[x + y * stride2];
+                s1 += a;
+                s2 += b;
+                ss += a * a;
+                ss += b * b;
+                s12 += a * b;
+            }
+        sums[z][0] = s1;
+        sums[z][1] = s2;
+        sums[z][2] = ss;
+        sums[z][3] = s12;
+        pix1 += 4;
+        pix2 += 4;
+    }
+}
+
+template<class T1>
+float ssim_end_4(T1 sum0[5][4], T1 sum1[5][4], int width)
+{
+    float ssim = 0.0;
+    for (int i = 0; i < width; i++)
+        ssim += ssim_end_1(sum0[i][0] + sum0[i+1][0] + sum1[i][0] + sum1[i+1][0],
+                          sum0[i][1] + sum0[i+1][1] + sum1[i][1] + sum1[i+1][1],
+                          sum0[i][2] + sum0[i+1][2] + sum1[i][2] + sum1[i+1][2],
+                          sum0[i][3] + sum0[i+1][3] + sum1[i][3] + sum1[i+1][3]);
+    return ssim;
+}
+
+template<class T1>
+float ssim_end_1(T1 s1, T1 s2, T1 ss, T1 s12)
+{
+    static const uint16_t pixelMax = (1 << X265_DEPTH)-1;
+#if HIGH_BIT_DEPTH
+    static const float ssim_c1 = .01 * .01 * pixelMax * pixelMax * 64;
+    static const float ssim_c2 = .03 * .03 * pixelMax * pixelMax * 64 * 63;
+#else
+    static const int ssim_c1 = (int)(.01 *.01 * pixelMax * pixelMax * 64 + .5);
+    static const int ssim_c2 = (int)(.03 * .03 * pixelMax * pixelMax * 64 * 63 + .5);
+#endif
+    T1 fs1 = s1;
+    T1 fs2 = s2;
+    T1 fss = ss;
+    T1 fs12 = s12;
+    T1 vars = fss * 64 - fs1 * fs1 - fs2 * fs2;
+    T1 covar = fs12 * 64 - fs1 * fs2;
+    return (float)(2 * fs1 * fs2 + ssim_c1) * (float)(2 * covar + ssim_c2)
+         / ((float)(fs1 * fs1 + fs2 * fs2 + ssim_c1) * (float)(vars + ssim_c2));
+#undef type
+}
+
+
+
 }  // end anonymous namespace
 
 namespace x265 {
@@ -851,5 +914,10 @@
     p.scale1D_128to64 = scale1D_128to64;
     p.scale2D_64to32 = scale2D_64to32;
     p.frame_init_lowres_core = frame_init_lowres_core;
+
+    p.ssim_4x4x2_core_hb = ssim_4x4x2_core<float>;
+    p.ssim_4x4x2_core_lb = ssim_4x4x2_core<int>;
+    p.ssim_end4_hb     = ssim_end_4<float>;
+    p.ssim_end4_lb     = ssim_end_4<int>;
 }
 }
diff -r fc225ea42650 -r bc38d5144033 source/common/primitives.h
--- a/source/common/primitives.h	Tue Oct 01 17:28:19 2013 +0530
+++ b/source/common/primitives.h	Tue Oct 01 17:37:13 2013 +0530
@@ -233,6 +233,10 @@
 typedef void (*scale_t)(pixel *dst, pixel *src, intptr_t stride);
 typedef void (*downscale_t)(pixel *src0, pixel *dstf, pixel *dsth, pixel *dstv, pixel *dstc,
                             intptr_t src_stride, intptr_t dst_stride, int width, int height);
+typedef void (*ssim_4x4x2_core_lb_t)(const pixel *pix1, intptr_t stride1, const pixel *pix2, intptr_t stride2, int sums[2][4]);
+typedef void (*ssim_4x4x2_core_hb_t)(const pixel *pix1, intptr_t stride1, const pixel *pix2, intptr_t stride2, float sums[2][4]);
+typedef float (*ssim_end4_lb_t)(int sum0[5][4], int sum1[5][4], int width);
+typedef float (*ssim_end4_hb_t)(float sum0[5][4], float sum1[5][4], int width);
 
 /* Define a structure containing function pointers to optimized encoder
  * primitives.  Each pointer can reference either an assembly routine,
@@ -297,6 +301,11 @@
     scale_t         scale1D_128to64;
     scale_t         scale2D_64to32;
     downscale_t     frame_init_lowres_core;
+
+    ssim_4x4x2_core_lb_t   ssim_4x4x2_core_lb;
+    ssim_4x4x2_core_hb_t   ssim_4x4x2_core_hb;
+    ssim_end4_lb_t         ssim_end4_lb;
+    ssim_end4_hb_t         ssim_end4_hb;
 };
 
 /* This copy of the table is what gets used by the encoder.