The Tor Browser: media/libyuv/util/ssim.cc@b8a032363ba2 (annotated)

media/libyuv/util/ssim.cc@b8a032363ba2 (annotated)

media/libyuv/util/ssim.cc

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  *  Copyright 2013 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "../util/ssim.h"  // NOLINT
 #include <math.h>
 #include <string.h>
 #ifdef __cplusplus
 extern "C" {
 #endif
 typedef unsigned int uint32;     // NOLINT
 typedef unsigned short uint16;   // NOLINT
 #if !defined(LIBYUV_DISABLE_X86) && !defined(__SSE2__) && \
   (defined(_M_X64) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 2)))
 #define __SSE2__
 #endif
 #if !defined(LIBYUV_DISABLE_X86) && defined(__SSE2__)
 #include <emmintrin.h>
 #endif
 #ifdef _OPENMP
 #include <omp.h>
 #endif
 // SSIM
 enum { KERNEL = 3, KERNEL_SIZE = 2 * KERNEL + 1 };
 // Symmetric Gaussian kernel:  K[i] = ~11 * exp(-0.3 * i * i)
 // The maximum value (11 x 11) must be less than 128 to avoid sign
 // problems during the calls to _mm_mullo_epi16().
 static const int K[KERNEL_SIZE] = {
 , 3, 7, 11, 7, 3, 1    // ~11 * exp(-0.3 * i * i)
 };
 static const double kiW[KERNEL + 1 + 1] = {
 . / 1089.,   // 1 / sum(i:0..6, j..6) K[i]*K[j]
 . / 1089.,   // 1 / sum(i:0..6, j..6) K[i]*K[j]
 . / 1056.,   // 1 / sum(i:0..5, j..6) K[i]*K[j]
 . / 957.,    // 1 / sum(i:0..4, j..6) K[i]*K[j]
 . / 726.,    // 1 / sum(i:0..3, j..6) K[i]*K[j]
 };
 #if !defined(LIBYUV_DISABLE_X86) && defined(__SSE2__)
 #define PWEIGHT(A, B)  static_cast<uint16>(K[(A)] * K[(B)])   // weight product
 #define MAKE_WEIGHT(L)                                               \
   { { { PWEIGHT(L, 0), PWEIGHT(L, 1), PWEIGHT(L, 2), PWEIGHT(L, 3),  \
         PWEIGHT(L, 4), PWEIGHT(L, 5), PWEIGHT(L, 6), 0 } } }
 // We need this union trick to be able to initialize constant static __m128i
 // values. We can't call _mm_set_epi16() for static compile-time initialization.
 static const struct {
   union {
     uint16 i16_[8];
     __m128i m_;
   } values_;
 } W0 = MAKE_WEIGHT(0),
   W1 = MAKE_WEIGHT(1),
   W2 = MAKE_WEIGHT(2),
   W3 = MAKE_WEIGHT(3);
   // ... the rest is symmetric.
 #undef MAKE_WEIGHT
 #undef PWEIGHT
 #endif
 // Common final expression for SSIM, once the weighted sums are known.
 static double FinalizeSSIM(double iw, double xm, double ym,
                            double xxm, double xym, double yym) {
   const double iwx = xm * iw;
   const double iwy = ym * iw;
   double sxx = xxm * iw - iwx * iwx;
   double syy = yym * iw - iwy * iwy;
   // small errors are possible, due to rounding. Clamp to zero.
   if (sxx < 0.) sxx = 0.;
   if (syy < 0.) syy = 0.;
   const double sxsy = sqrt(sxx * syy);
   const double sxy = xym * iw - iwx * iwy;
   static const double C11 = (0.01 * 0.01) * (255 * 255);
   static const double C22 = (0.03 * 0.03) * (255 * 255);
   static const double C33 = (0.015 * 0.015) * (255 * 255);
   const double l = (2. * iwx * iwy + C11) / (iwx * iwx + iwy * iwy + C11);
   const double c = (2. * sxsy      + C22) / (sxx + syy + C22);
   const double s = (sxy + C33) / (sxsy + C33);
   return l * c * s;
 }
 // GetSSIM() does clipping.  GetSSIMFullKernel() does not
 // TODO(skal): use summed tables?
 // Note: worst case of accumulation is a weight of 33 = 11 + 2 * (7 + 3 + 1)
 // with a diff of 255, squared. The maximum error is thus 0x4388241,
 // which fits into 32 bits integers.
 double GetSSIM(const uint8 *org, const uint8 *rec,
                int xo, int yo, int W, int H, int stride) {
   uint32 ws = 0, xm = 0, ym = 0, xxm = 0, xym = 0, yym = 0;
   org += (yo - KERNEL) * stride;
   org += (xo - KERNEL);
   rec += (yo - KERNEL) * stride;
   rec += (xo - KERNEL);
   for (int y_ = 0; y_ < KERNEL_SIZE; ++y_, org += stride, rec += stride) {
     if (((yo - KERNEL + y_) < 0) || ((yo - KERNEL + y_) >= H)) continue;
     const int Wy = K[y_];
     for (int x_ = 0; x_ < KERNEL_SIZE; ++x_) {
       const int Wxy = Wy * K[x_];
       if (((xo - KERNEL + x_) >= 0) && ((xo - KERNEL + x_) < W)) {
         const int org_x = org[x_];
         const int rec_x = rec[x_];
         ws += Wxy;
         xm  += Wxy * org_x;
         ym  += Wxy * rec_x;
         xxm += Wxy * org_x * org_x;
         xym += Wxy * org_x * rec_x;
         yym += Wxy * rec_x * rec_x;
       }
     }
   }
   return FinalizeSSIM(1. / ws, xm, ym, xxm, xym, yym);
 }
 double GetSSIMFullKernel(const uint8 *org, const uint8 *rec,
                          int xo, int yo, int stride,
                          double area_weight) {
   uint32 xm = 0, ym = 0, xxm = 0, xym = 0, yym = 0;
 #if defined(LIBYUV_DISABLE_X86) || !defined(__SSE2__)
   org += yo * stride + xo;
   rec += yo * stride + xo;
   for (int y = 1; y <= KERNEL; y++) {
     const int dy1 = y * stride;
     const int dy2 = y * stride;
     const int Wy = K[KERNEL + y];
     for (int x = 1; x <= KERNEL; x++) {
       // Compute the contributions of upper-left (ul), upper-right (ur)
       // lower-left (ll) and lower-right (lr) points (see the diagram below).
       // Symmetric Kernel will have same weight on those points.
       //       -  -  -  -  -  -  -
       //       -  ul -  -  -  ur -
       //       -  -  -  -  -  -  -
       //       -  -  -  0  -  -  -
       //       -  -  -  -  -  -  -
       //       -  ll -  -  -  lr -
       //       -  -  -  -  -  -  -
       const int Wxy = Wy * K[KERNEL + x];
       const int ul1 = org[-dy1 - x];
       const int ur1 = org[-dy1 + x];
       const int ll1 = org[dy1 - x];
       const int lr1 = org[dy1 + x];
       const int ul2 = rec[-dy2 - x];
       const int ur2 = rec[-dy2 + x];
       const int ll2 = rec[dy2 - x];
       const int lr2 = rec[dy2 + x];
       xm  += Wxy * (ul1 + ur1 + ll1 + lr1);
       ym  += Wxy * (ul2 + ur2 + ll2 + lr2);
       xxm += Wxy * (ul1 * ul1 + ur1 * ur1 + ll1 * ll1 + lr1 * lr1);
       xym += Wxy * (ul1 * ul2 + ur1 * ur2 + ll1 * ll2 + lr1 * lr2);
       yym += Wxy * (ul2 * ul2 + ur2 * ur2 + ll2 * ll2 + lr2 * lr2);
     }
     // Compute the contributions of up (u), down (d), left (l) and right (r)
     // points across the main axes (see the diagram below).
     // Symmetric Kernel will have same weight on those points.
     //       -  -  -  -  -  -  -
     //       -  -  -  u  -  -  -
     //       -  -  -  -  -  -  -
     //       -  l  -  0  -  r  -
     //       -  -  -  -  -  -  -
     //       -  -  -  d  -  -  -
     //       -  -  -  -  -  -  -
     const int Wxy = Wy * K[KERNEL];
     const int u1 = org[-dy1];
     const int d1 = org[dy1];
     const int l1 = org[-y];
     const int r1 = org[y];
     const int u2 = rec[-dy2];
     const int d2 = rec[dy2];
     const int l2 = rec[-y];
     const int r2 = rec[y];
     xm  += Wxy * (u1 + d1 + l1 + r1);
     ym  += Wxy * (u2 + d2 + l2 + r2);
     xxm += Wxy * (u1 * u1 + d1 * d1 + l1 * l1 + r1 * r1);
     xym += Wxy * (u1 * u2 + d1 * d2 + l1 * l2 + r1 * r2);
     yym += Wxy * (u2 * u2 + d2 * d2 + l2 * l2 + r2 * r2);
   }
   // Lastly the contribution of (x0, y0) point.
   const int Wxy = K[KERNEL] * K[KERNEL];
   const int s1 = org[0];
   const int s2 = rec[0];
   xm  += Wxy * s1;
   ym  += Wxy * s2;
   xxm += Wxy * s1 * s1;
   xym += Wxy * s1 * s2;
   yym += Wxy * s2 * s2;
 #else   // __SSE2__
   org += (yo - KERNEL) * stride + (xo - KERNEL);
   rec += (yo - KERNEL) * stride + (xo - KERNEL);
   const __m128i zero = _mm_setzero_si128();
   __m128i x = zero;
   __m128i y = zero;
   __m128i xx = zero;
   __m128i xy = zero;
   __m128i yy = zero;
 // Read 8 pixels at line #L, and convert to 16bit, perform weighting
 // and acccumulate.
 #define LOAD_LINE_PAIR(L, WEIGHT) do {                                       \
   const __m128i v0 =                                                         \
       _mm_loadl_epi64(reinterpret_cast<const __m128i*>(org + (L) * stride)); \
   const __m128i v1 =                                                         \
       _mm_loadl_epi64(reinterpret_cast<const __m128i*>(rec + (L) * stride)); \
   const __m128i w0 = _mm_unpacklo_epi8(v0, zero);                            \
   const __m128i w1 = _mm_unpacklo_epi8(v1, zero);                            \
   const __m128i ww0 = _mm_mullo_epi16(w0, (WEIGHT).values_.m_);              \
   const __m128i ww1 = _mm_mullo_epi16(w1, (WEIGHT).values_.m_);              \
   x = _mm_add_epi32(x, _mm_unpacklo_epi16(ww0, zero));                       \
   y = _mm_add_epi32(y, _mm_unpacklo_epi16(ww1, zero));                       \
   x = _mm_add_epi32(x, _mm_unpackhi_epi16(ww0, zero));                       \
   y = _mm_add_epi32(y, _mm_unpackhi_epi16(ww1, zero));                       \
   xx = _mm_add_epi32(xx, _mm_madd_epi16(ww0, w0));                           \
   xy = _mm_add_epi32(xy, _mm_madd_epi16(ww0, w1));                           \
   yy = _mm_add_epi32(yy, _mm_madd_epi16(ww1, w1));                           \
 } while (0)
 #define ADD_AND_STORE_FOUR_EPI32(M, OUT) do {                                \
   uint32 tmp[4];                                                             \
   _mm_storeu_si128(reinterpret_cast<__m128i*>(tmp), (M));                    \
   (OUT) = tmp[3] + tmp[2] + tmp[1] + tmp[0];                                 \
 } while (0)
   LOAD_LINE_PAIR(0, W0);
   LOAD_LINE_PAIR(1, W1);
   LOAD_LINE_PAIR(2, W2);
   LOAD_LINE_PAIR(3, W3);
   LOAD_LINE_PAIR(4, W2);
   LOAD_LINE_PAIR(5, W1);
   LOAD_LINE_PAIR(6, W0);
   ADD_AND_STORE_FOUR_EPI32(x, xm);
   ADD_AND_STORE_FOUR_EPI32(y, ym);
   ADD_AND_STORE_FOUR_EPI32(xx, xxm);
   ADD_AND_STORE_FOUR_EPI32(xy, xym);
   ADD_AND_STORE_FOUR_EPI32(yy, yym);
 #undef LOAD_LINE_PAIR
 #undef ADD_AND_STORE_FOUR_EPI32
 #endif
   return FinalizeSSIM(area_weight, xm, ym, xxm, xym, yym);
 }
 static int start_max(int x, int y) { return (x > y) ? x : y; }
 double CalcSSIM(const uint8 *org, const uint8 *rec,
                 const int image_width, const int image_height) {
   double SSIM = 0.;
   const int KERNEL_Y = (image_height < KERNEL) ? image_height : KERNEL;
   const int KERNEL_X = (image_width < KERNEL) ? image_width : KERNEL;
   const int start_x = start_max(image_width - 8 + KERNEL_X, KERNEL_X);
   const int start_y = start_max(image_height - KERNEL_Y, KERNEL_Y);
   const int stride = image_width;
   for (int j = 0; j < KERNEL_Y; ++j) {
     for (int i = 0; i < image_width; ++i) {
       SSIM += GetSSIM(org, rec, i, j, image_width, image_height, stride);
     }
   }
 #ifdef _OPENMP
   #pragma omp parallel for reduction(+: SSIM)
 #endif
   for (int j = KERNEL_Y; j < image_height - KERNEL_Y; ++j) {
     for (int i = 0; i < KERNEL_X; ++i) {
       SSIM += GetSSIM(org, rec, i, j, image_width, image_height, stride);
     }
     for (int i = KERNEL_X; i < start_x; ++i) {
       SSIM += GetSSIMFullKernel(org, rec, i, j, stride, kiW[0]);
     }
     if (start_x < image_width) {
       // GetSSIMFullKernel() needs to be able to read 8 pixels (in SSE2). So we
       // copy the 8 rightmost pixels on a cache area, and pad this area with
       // zeros which won't contribute to the overall SSIM value (but we need
       // to pass the correct normalizing constant!). By using this cache, we can
       // still call GetSSIMFullKernel() instead of the slower GetSSIM().
       // NOTE: we could use similar method for the left-most pixels too.
       const int kScratchWidth = 8;
       const int kScratchStride = kScratchWidth + KERNEL + 1;
       uint8 scratch_org[KERNEL_SIZE * kScratchStride] = { 0 };
       uint8 scratch_rec[KERNEL_SIZE * kScratchStride] = { 0 };
       for (int k = 0; k < KERNEL_SIZE; ++k) {
         const int offset =
             (j - KERNEL + k) * stride + image_width - kScratchWidth;
         memcpy(scratch_org + k * kScratchStride, org + offset, kScratchWidth);
         memcpy(scratch_rec + k * kScratchStride, rec + offset, kScratchWidth);
       }
       for (int k = 0;  k <= KERNEL_X + 1; ++k) {
         SSIM += GetSSIMFullKernel(scratch_org, scratch_rec,
                                   KERNEL + k, KERNEL, kScratchStride, kiW[k]);
       }
     }
   }
   for (int j = start_y; j < image_height; ++j) {
     for (int i = 0; i < image_width; ++i) {
       SSIM += GetSSIM(org, rec, i, j, image_width, image_height, stride);
     }
   }
   return SSIM;
 }
 double CalcLSSIM(double ssim) {
   return -10.0 * log10(1.0 - ssim);
 }
 #ifdef __cplusplus
 }  // extern "C"
 #endif

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media/libyuv/util/ssim.cc