1 // Copyright 2014 Google Inc. All Rights Reserved. 2 // 3 // Use of this source code is governed by a BSD-style license 4 // that can be found in the COPYING file in the root of the source 5 // tree. An additional intellectual property rights grant can be found 6 // in the file PATENTS. All contributing project authors may 7 // be found in the AUTHORS file in the root of the source tree. 8 // ----------------------------------------------------------------------------- 9 // 10 // WebPPicture tools for measuring distortion 11 // 12 // Author: Skal (pascal.massimino (at) gmail.com) 13 14 #include <math.h> 15 16 #include "./vp8enci.h" 17 18 //------------------------------------------------------------------------------ 19 // local-min distortion 20 // 21 // For every pixel in the *reference* picture, we search for the local best 22 // match in the compressed image. This is not a symmetrical measure. 23 24 #define RADIUS 2 // search radius. Shouldn't be too large. 25 26 static float AccumulateLSIM(const uint8_t* src, int src_stride, 27 const uint8_t* ref, int ref_stride, 28 int w, int h) { 29 int x, y; 30 double total_sse = 0.; 31 for (y = 0; y < h; ++y) { 32 const int y_0 = (y - RADIUS < 0) ? 0 : y - RADIUS; 33 const int y_1 = (y + RADIUS + 1 >= h) ? h : y + RADIUS + 1; 34 for (x = 0; x < w; ++x) { 35 const int x_0 = (x - RADIUS < 0) ? 0 : x - RADIUS; 36 const int x_1 = (x + RADIUS + 1 >= w) ? w : x + RADIUS + 1; 37 double best_sse = 255. * 255.; 38 const double value = (double)ref[y * ref_stride + x]; 39 int i, j; 40 for (j = y_0; j < y_1; ++j) { 41 const uint8_t* s = src + j * src_stride; 42 for (i = x_0; i < x_1; ++i) { 43 const double sse = (double)(s[i] - value) * (s[i] - value); 44 if (sse < best_sse) best_sse = sse; 45 } 46 } 47 total_sse += best_sse; 48 } 49 } 50 return (float)total_sse; 51 } 52 #undef RADIUS 53 54 //------------------------------------------------------------------------------ 55 // Distortion 56 57 // Max value returned in case of exact similarity. 58 static const double kMinDistortion_dB = 99.; 59 static float GetPSNR(const double v) { 60 return (float)((v > 0.) ? -4.3429448 * log(v / (255 * 255.)) 61 : kMinDistortion_dB); 62 } 63 64 int WebPPictureDistortion(const WebPPicture* src, const WebPPicture* ref, 65 int type, float result[5]) { 66 DistoStats stats[5]; 67 int has_alpha; 68 int uv_w, uv_h; 69 70 if (src == NULL || ref == NULL || 71 src->width != ref->width || src->height != ref->height || 72 src->y == NULL || ref->y == NULL || 73 src->u == NULL || ref->u == NULL || 74 src->v == NULL || ref->v == NULL || 75 result == NULL) { 76 return 0; 77 } 78 // TODO(skal): provide distortion for ARGB too. 79 if (src->use_argb == 1 || src->use_argb != ref->use_argb) { 80 return 0; 81 } 82 83 has_alpha = !!(src->colorspace & WEBP_CSP_ALPHA_BIT); 84 if (has_alpha != !!(ref->colorspace & WEBP_CSP_ALPHA_BIT) || 85 (has_alpha && (src->a == NULL || ref->a == NULL))) { 86 return 0; 87 } 88 89 memset(stats, 0, sizeof(stats)); 90 91 uv_w = (src->width + 1) >> 1; 92 uv_h = (src->height + 1) >> 1; 93 if (type >= 2) { 94 float sse[4]; 95 sse[0] = AccumulateLSIM(src->y, src->y_stride, 96 ref->y, ref->y_stride, src->width, src->height); 97 sse[1] = AccumulateLSIM(src->u, src->uv_stride, 98 ref->u, ref->uv_stride, uv_w, uv_h); 99 sse[2] = AccumulateLSIM(src->v, src->uv_stride, 100 ref->v, ref->uv_stride, uv_w, uv_h); 101 sse[3] = has_alpha ? AccumulateLSIM(src->a, src->a_stride, 102 ref->a, ref->a_stride, 103 src->width, src->height) 104 : 0.f; 105 result[0] = GetPSNR(sse[0] / (src->width * src->height)); 106 result[1] = GetPSNR(sse[1] / (uv_w * uv_h)); 107 result[2] = GetPSNR(sse[2] / (uv_w * uv_h)); 108 result[3] = GetPSNR(sse[3] / (src->width * src->height)); 109 { 110 double total_sse = sse[0] + sse[1] + sse[2]; 111 int total_pixels = src->width * src->height + 2 * uv_w * uv_h; 112 if (has_alpha) { 113 total_pixels += src->width * src->height; 114 total_sse += sse[3]; 115 } 116 result[4] = GetPSNR(total_sse / total_pixels); 117 } 118 } else { 119 int c; 120 VP8SSIMAccumulatePlane(src->y, src->y_stride, 121 ref->y, ref->y_stride, 122 src->width, src->height, &stats[0]); 123 VP8SSIMAccumulatePlane(src->u, src->uv_stride, 124 ref->u, ref->uv_stride, 125 uv_w, uv_h, &stats[1]); 126 VP8SSIMAccumulatePlane(src->v, src->uv_stride, 127 ref->v, ref->uv_stride, 128 uv_w, uv_h, &stats[2]); 129 if (has_alpha) { 130 VP8SSIMAccumulatePlane(src->a, src->a_stride, 131 ref->a, ref->a_stride, 132 src->width, src->height, &stats[3]); 133 } 134 for (c = 0; c <= 4; ++c) { 135 if (type == 1) { 136 const double v = VP8SSIMGet(&stats[c]); 137 result[c] = (float)((v < 1.) ? -10.0 * log10(1. - v) 138 : kMinDistortion_dB); 139 } else { 140 const double v = VP8SSIMGetSquaredError(&stats[c]); 141 result[c] = GetPSNR(v); 142 } 143 // Accumulate forward 144 if (c < 4) VP8SSIMAddStats(&stats[c], &stats[4]); 145 } 146 } 147 return 1; 148 } 149 150 //------------------------------------------------------------------------------ 151
