462 lines
17 KiB
C
462 lines
17 KiB
C
/*
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* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include <assert.h>
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#include <math.h>
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#include "./vpx_dsp_rtcd.h"
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#include "vpx_dsp/ssim.h"
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#include "vpx_ports/mem.h"
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#include "vpx_ports/system_state.h"
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void vpx_ssim_parms_16x16_c(const uint8_t *s, int sp, const uint8_t *r, int rp,
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uint32_t *sum_s, uint32_t *sum_r,
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uint32_t *sum_sq_s, uint32_t *sum_sq_r,
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uint32_t *sum_sxr) {
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int i, j;
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for (i = 0; i < 16; i++, s += sp, r += rp) {
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for (j = 0; j < 16; j++) {
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*sum_s += s[j];
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*sum_r += r[j];
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*sum_sq_s += s[j] * s[j];
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*sum_sq_r += r[j] * r[j];
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*sum_sxr += s[j] * r[j];
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}
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}
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}
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void vpx_ssim_parms_8x8_c(const uint8_t *s, int sp, const uint8_t *r, int rp,
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uint32_t *sum_s, uint32_t *sum_r, uint32_t *sum_sq_s,
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uint32_t *sum_sq_r, uint32_t *sum_sxr) {
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int i, j;
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for (i = 0; i < 8; i++, s += sp, r += rp) {
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for (j = 0; j < 8; j++) {
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*sum_s += s[j];
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*sum_r += r[j];
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*sum_sq_s += s[j] * s[j];
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*sum_sq_r += r[j] * r[j];
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*sum_sxr += s[j] * r[j];
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}
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}
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}
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#if CONFIG_VP9_HIGHBITDEPTH
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void vpx_highbd_ssim_parms_8x8_c(const uint16_t *s, int sp, const uint16_t *r,
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int rp, uint32_t *sum_s, uint32_t *sum_r,
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uint32_t *sum_sq_s, uint32_t *sum_sq_r,
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uint32_t *sum_sxr) {
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int i, j;
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for (i = 0; i < 8; i++, s += sp, r += rp) {
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for (j = 0; j < 8; j++) {
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*sum_s += s[j];
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*sum_r += r[j];
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*sum_sq_s += s[j] * s[j];
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*sum_sq_r += r[j] * r[j];
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*sum_sxr += s[j] * r[j];
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}
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}
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}
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#endif // CONFIG_VP9_HIGHBITDEPTH
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static const int64_t cc1 = 26634; // (64^2*(.01*255)^2
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static const int64_t cc2 = 239708; // (64^2*(.03*255)^2
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static const int64_t cc1_10 = 428658; // (64^2*(.01*1023)^2
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static const int64_t cc2_10 = 3857925; // (64^2*(.03*1023)^2
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static const int64_t cc1_12 = 6868593; // (64^2*(.01*4095)^2
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static const int64_t cc2_12 = 61817334; // (64^2*(.03*4095)^2
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static double similarity(uint32_t sum_s, uint32_t sum_r, uint32_t sum_sq_s,
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uint32_t sum_sq_r, uint32_t sum_sxr, int count,
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uint32_t bd) {
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int64_t ssim_n, ssim_d;
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int64_t c1, c2;
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if (bd == 8) {
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// scale the constants by number of pixels
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c1 = (cc1 * count * count) >> 12;
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c2 = (cc2 * count * count) >> 12;
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} else if (bd == 10) {
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c1 = (cc1_10 * count * count) >> 12;
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c2 = (cc2_10 * count * count) >> 12;
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} else if (bd == 12) {
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c1 = (cc1_12 * count * count) >> 12;
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c2 = (cc2_12 * count * count) >> 12;
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} else {
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c1 = c2 = 0;
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assert(0);
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}
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ssim_n = (2 * sum_s * sum_r + c1) *
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((int64_t)2 * count * sum_sxr - (int64_t)2 * sum_s * sum_r + c2);
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ssim_d = (sum_s * sum_s + sum_r * sum_r + c1) *
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((int64_t)count * sum_sq_s - (int64_t)sum_s * sum_s +
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(int64_t)count * sum_sq_r - (int64_t)sum_r * sum_r + c2);
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return ssim_n * 1.0 / ssim_d;
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}
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static double ssim_8x8(const uint8_t *s, int sp, const uint8_t *r, int rp) {
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uint32_t sum_s = 0, sum_r = 0, sum_sq_s = 0, sum_sq_r = 0, sum_sxr = 0;
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vpx_ssim_parms_8x8(s, sp, r, rp, &sum_s, &sum_r, &sum_sq_s, &sum_sq_r,
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&sum_sxr);
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return similarity(sum_s, sum_r, sum_sq_s, sum_sq_r, sum_sxr, 64, 8);
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}
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#if CONFIG_VP9_HIGHBITDEPTH
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static double highbd_ssim_8x8(const uint16_t *s, int sp, const uint16_t *r,
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int rp, uint32_t bd, uint32_t shift) {
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uint32_t sum_s = 0, sum_r = 0, sum_sq_s = 0, sum_sq_r = 0, sum_sxr = 0;
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vpx_highbd_ssim_parms_8x8(s, sp, r, rp, &sum_s, &sum_r, &sum_sq_s, &sum_sq_r,
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&sum_sxr);
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return similarity(sum_s >> shift, sum_r >> shift, sum_sq_s >> (2 * shift),
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sum_sq_r >> (2 * shift), sum_sxr >> (2 * shift), 64, bd);
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}
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#endif // CONFIG_VP9_HIGHBITDEPTH
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// We are using a 8x8 moving window with starting location of each 8x8 window
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// on the 4x4 pixel grid. Such arrangement allows the windows to overlap
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// block boundaries to penalize blocking artifacts.
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static double vpx_ssim2(const uint8_t *img1, const uint8_t *img2,
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int stride_img1, int stride_img2, int width,
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int height) {
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int i, j;
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int samples = 0;
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double ssim_total = 0;
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// sample point start with each 4x4 location
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for (i = 0; i <= height - 8;
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i += 4, img1 += stride_img1 * 4, img2 += stride_img2 * 4) {
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for (j = 0; j <= width - 8; j += 4) {
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double v = ssim_8x8(img1 + j, stride_img1, img2 + j, stride_img2);
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ssim_total += v;
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samples++;
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}
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}
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ssim_total /= samples;
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return ssim_total;
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}
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#if CONFIG_VP9_HIGHBITDEPTH
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static double vpx_highbd_ssim2(const uint8_t *img1, const uint8_t *img2,
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int stride_img1, int stride_img2, int width,
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int height, uint32_t bd, uint32_t shift) {
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int i, j;
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int samples = 0;
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double ssim_total = 0;
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// sample point start with each 4x4 location
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for (i = 0; i <= height - 8;
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i += 4, img1 += stride_img1 * 4, img2 += stride_img2 * 4) {
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for (j = 0; j <= width - 8; j += 4) {
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double v = highbd_ssim_8x8(CONVERT_TO_SHORTPTR(img1 + j), stride_img1,
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CONVERT_TO_SHORTPTR(img2 + j), stride_img2, bd,
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shift);
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ssim_total += v;
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samples++;
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}
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}
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ssim_total /= samples;
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return ssim_total;
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}
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#endif // CONFIG_VP9_HIGHBITDEPTH
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double vpx_calc_ssim(const YV12_BUFFER_CONFIG *source,
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const YV12_BUFFER_CONFIG *dest, double *weight) {
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double a, b, c;
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double ssimv;
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a = vpx_ssim2(source->y_buffer, dest->y_buffer, source->y_stride,
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dest->y_stride, source->y_crop_width, source->y_crop_height);
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b = vpx_ssim2(source->u_buffer, dest->u_buffer, source->uv_stride,
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dest->uv_stride, source->uv_crop_width, source->uv_crop_height);
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c = vpx_ssim2(source->v_buffer, dest->v_buffer, source->uv_stride,
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dest->uv_stride, source->uv_crop_width, source->uv_crop_height);
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ssimv = a * .8 + .1 * (b + c);
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*weight = 1;
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return ssimv;
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}
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// traditional ssim as per: http://en.wikipedia.org/wiki/Structural_similarity
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//
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// Re working out the math ->
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//
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// ssim(x,y) = (2*mean(x)*mean(y) + c1)*(2*cov(x,y)+c2) /
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// ((mean(x)^2+mean(y)^2+c1)*(var(x)+var(y)+c2))
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//
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// mean(x) = sum(x) / n
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//
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// cov(x,y) = (n*sum(xi*yi)-sum(x)*sum(y))/(n*n)
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//
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// var(x) = (n*sum(xi*xi)-sum(xi)*sum(xi))/(n*n)
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//
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// ssim(x,y) =
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// (2*sum(x)*sum(y)/(n*n) + c1)*(2*(n*sum(xi*yi)-sum(x)*sum(y))/(n*n)+c2) /
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// (((sum(x)*sum(x)+sum(y)*sum(y))/(n*n) +c1) *
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// ((n*sum(xi*xi) - sum(xi)*sum(xi))/(n*n)+
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// (n*sum(yi*yi) - sum(yi)*sum(yi))/(n*n)+c2)))
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//
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// factoring out n*n
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//
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// ssim(x,y) =
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// (2*sum(x)*sum(y) + n*n*c1)*(2*(n*sum(xi*yi)-sum(x)*sum(y))+n*n*c2) /
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// (((sum(x)*sum(x)+sum(y)*sum(y)) + n*n*c1) *
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// (n*sum(xi*xi)-sum(xi)*sum(xi)+n*sum(yi*yi)-sum(yi)*sum(yi)+n*n*c2))
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//
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// Replace c1 with n*n * c1 for the final step that leads to this code:
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// The final step scales by 12 bits so we don't lose precision in the constants.
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static double ssimv_similarity(const Ssimv *sv, int64_t n) {
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// Scale the constants by number of pixels.
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const int64_t c1 = (cc1 * n * n) >> 12;
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const int64_t c2 = (cc2 * n * n) >> 12;
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const double l = 1.0 * (2 * sv->sum_s * sv->sum_r + c1) /
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(sv->sum_s * sv->sum_s + sv->sum_r * sv->sum_r + c1);
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// Since these variables are unsigned sums, convert to double so
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// math is done in double arithmetic.
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const double v = (2.0 * n * sv->sum_sxr - 2 * sv->sum_s * sv->sum_r + c2) /
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(n * sv->sum_sq_s - sv->sum_s * sv->sum_s +
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n * sv->sum_sq_r - sv->sum_r * sv->sum_r + c2);
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return l * v;
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}
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// The first term of the ssim metric is a luminance factor.
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//
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// (2*mean(x)*mean(y) + c1)/ (mean(x)^2+mean(y)^2+c1)
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//
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// This luminance factor is super sensitive to the dark side of luminance
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// values and completely insensitive on the white side. check out 2 sets
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// (1,3) and (250,252) the term gives ( 2*1*3/(1+9) = .60
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// 2*250*252/ (250^2+252^2) => .99999997
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//
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// As a result in this tweaked version of the calculation in which the
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// luminance is taken as percentage off from peak possible.
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//
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// 255 * 255 - (sum_s - sum_r) / count * (sum_s - sum_r) / count
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//
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static double ssimv_similarity2(const Ssimv *sv, int64_t n) {
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// Scale the constants by number of pixels.
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const int64_t c1 = (cc1 * n * n) >> 12;
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const int64_t c2 = (cc2 * n * n) >> 12;
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const double mean_diff = (1.0 * sv->sum_s - sv->sum_r) / n;
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const double l = (255 * 255 - mean_diff * mean_diff + c1) / (255 * 255 + c1);
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// Since these variables are unsigned, sums convert to double so
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// math is done in double arithmetic.
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const double v = (2.0 * n * sv->sum_sxr - 2 * sv->sum_s * sv->sum_r + c2) /
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(n * sv->sum_sq_s - sv->sum_s * sv->sum_s +
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n * sv->sum_sq_r - sv->sum_r * sv->sum_r + c2);
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return l * v;
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}
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static void ssimv_parms(uint8_t *img1, int img1_pitch, uint8_t *img2,
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int img2_pitch, Ssimv *sv) {
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vpx_ssim_parms_8x8(img1, img1_pitch, img2, img2_pitch, &sv->sum_s, &sv->sum_r,
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&sv->sum_sq_s, &sv->sum_sq_r, &sv->sum_sxr);
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}
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double vpx_get_ssim_metrics(uint8_t *img1, int img1_pitch, uint8_t *img2,
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int img2_pitch, int width, int height, Ssimv *sv2,
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Metrics *m, int do_inconsistency) {
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double dssim_total = 0;
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double ssim_total = 0;
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double ssim2_total = 0;
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double inconsistency_total = 0;
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int i, j;
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int c = 0;
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double norm;
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double old_ssim_total = 0;
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vpx_clear_system_state();
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// We can sample points as frequently as we like start with 1 per 4x4.
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for (i = 0; i < height;
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i += 4, img1 += img1_pitch * 4, img2 += img2_pitch * 4) {
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for (j = 0; j < width; j += 4, ++c) {
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Ssimv sv = { 0, 0, 0, 0, 0, 0 };
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double ssim;
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double ssim2;
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double dssim;
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uint32_t var_new;
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uint32_t var_old;
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uint32_t mean_new;
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uint32_t mean_old;
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double ssim_new;
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double ssim_old;
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// Not sure there's a great way to handle the edge pixels
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// in ssim when using a window. Seems biased against edge pixels
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// however you handle this. This uses only samples that are
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// fully in the frame.
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if (j + 8 <= width && i + 8 <= height) {
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ssimv_parms(img1 + j, img1_pitch, img2 + j, img2_pitch, &sv);
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}
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ssim = ssimv_similarity(&sv, 64);
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ssim2 = ssimv_similarity2(&sv, 64);
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sv.ssim = ssim2;
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// dssim is calculated to use as an actual error metric and
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// is scaled up to the same range as sum square error.
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// Since we are subsampling every 16th point maybe this should be
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// *16 ?
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dssim = 255 * 255 * (1 - ssim2) / 2;
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// Here I introduce a new error metric: consistency-weighted
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// SSIM-inconsistency. This metric isolates frames where the
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// SSIM 'suddenly' changes, e.g. if one frame in every 8 is much
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// sharper or blurrier than the others. Higher values indicate a
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// temporally inconsistent SSIM. There are two ideas at work:
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//
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// 1) 'SSIM-inconsistency': the total inconsistency value
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// reflects how much SSIM values are changing between this
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// source / reference frame pair and the previous pair.
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//
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// 2) 'consistency-weighted': weights de-emphasize areas in the
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// frame where the scene content has changed. Changes in scene
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// content are detected via changes in local variance and local
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// mean.
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//
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// Thus the overall measure reflects how inconsistent the SSIM
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// values are, over consistent regions of the frame.
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//
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// The metric has three terms:
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//
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// term 1 -> uses change in scene Variance to weight error score
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// 2 * var(Fi)*var(Fi-1) / (var(Fi)^2+var(Fi-1)^2)
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// larger changes from one frame to the next mean we care
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// less about consistency.
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//
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// term 2 -> uses change in local scene luminance to weight error
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// 2 * avg(Fi)*avg(Fi-1) / (avg(Fi)^2+avg(Fi-1)^2)
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// larger changes from one frame to the next mean we care
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// less about consistency.
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//
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// term3 -> measures inconsistency in ssim scores between frames
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// 1 - ( 2 * ssim(Fi)*ssim(Fi-1)/(ssim(Fi)^2+sssim(Fi-1)^2).
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//
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// This term compares the ssim score for the same location in 2
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// subsequent frames.
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var_new = sv.sum_sq_s - sv.sum_s * sv.sum_s / 64;
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var_old = sv2[c].sum_sq_s - sv2[c].sum_s * sv2[c].sum_s / 64;
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mean_new = sv.sum_s;
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mean_old = sv2[c].sum_s;
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ssim_new = sv.ssim;
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ssim_old = sv2[c].ssim;
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if (do_inconsistency) {
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// We do the metric once for every 4x4 block in the image. Since
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// we are scaling the error to SSE for use in a psnr calculation
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// 1.0 = 4x4x255x255 the worst error we can possibly have.
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static const double kScaling = 4. * 4 * 255 * 255;
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// The constants have to be non 0 to avoid potential divide by 0
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// issues other than that they affect kind of a weighting between
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// the terms. No testing of what the right terms should be has been
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// done.
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static const double c1 = 1, c2 = 1, c3 = 1;
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// This measures how much consistent variance is in two consecutive
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// source frames. 1.0 means they have exactly the same variance.
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const double variance_term =
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(2.0 * var_old * var_new + c1) /
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(1.0 * var_old * var_old + 1.0 * var_new * var_new + c1);
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// This measures how consistent the local mean are between two
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// consecutive frames. 1.0 means they have exactly the same mean.
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const double mean_term =
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(2.0 * mean_old * mean_new + c2) /
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(1.0 * mean_old * mean_old + 1.0 * mean_new * mean_new + c2);
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// This measures how consistent the ssims of two
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// consecutive frames is. 1.0 means they are exactly the same.
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double ssim_term =
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pow((2.0 * ssim_old * ssim_new + c3) /
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(ssim_old * ssim_old + ssim_new * ssim_new + c3),
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5);
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double this_inconsistency;
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// Floating point math sometimes makes this > 1 by a tiny bit.
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// We want the metric to scale between 0 and 1.0 so we can convert
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// it to an snr scaled value.
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if (ssim_term > 1) ssim_term = 1;
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// This converts the consistency metric to an inconsistency metric
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// ( so we can scale it like psnr to something like sum square error.
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// The reason for the variance and mean terms is the assumption that
|
|
// if there are big changes in the source we shouldn't penalize
|
|
// inconsistency in ssim scores a bit less as it will be less visible
|
|
// to the user.
|
|
this_inconsistency = (1 - ssim_term) * variance_term * mean_term;
|
|
|
|
this_inconsistency *= kScaling;
|
|
inconsistency_total += this_inconsistency;
|
|
}
|
|
sv2[c] = sv;
|
|
ssim_total += ssim;
|
|
ssim2_total += ssim2;
|
|
dssim_total += dssim;
|
|
|
|
old_ssim_total += ssim_old;
|
|
}
|
|
old_ssim_total += 0;
|
|
}
|
|
|
|
norm = 1. / (width / 4) / (height / 4);
|
|
ssim_total *= norm;
|
|
ssim2_total *= norm;
|
|
m->ssim2 = ssim2_total;
|
|
m->ssim = ssim_total;
|
|
if (old_ssim_total == 0) inconsistency_total = 0;
|
|
|
|
m->ssimc = inconsistency_total;
|
|
|
|
m->dssim = dssim_total;
|
|
return inconsistency_total;
|
|
}
|
|
|
|
#if CONFIG_VP9_HIGHBITDEPTH
|
|
double vpx_highbd_calc_ssim(const YV12_BUFFER_CONFIG *source,
|
|
const YV12_BUFFER_CONFIG *dest, double *weight,
|
|
uint32_t bd, uint32_t in_bd) {
|
|
double a, b, c;
|
|
double ssimv;
|
|
uint32_t shift = 0;
|
|
|
|
assert(bd >= in_bd);
|
|
shift = bd - in_bd;
|
|
|
|
a = vpx_highbd_ssim2(source->y_buffer, dest->y_buffer, source->y_stride,
|
|
dest->y_stride, source->y_crop_width,
|
|
source->y_crop_height, in_bd, shift);
|
|
|
|
b = vpx_highbd_ssim2(source->u_buffer, dest->u_buffer, source->uv_stride,
|
|
dest->uv_stride, source->uv_crop_width,
|
|
source->uv_crop_height, in_bd, shift);
|
|
|
|
c = vpx_highbd_ssim2(source->v_buffer, dest->v_buffer, source->uv_stride,
|
|
dest->uv_stride, source->uv_crop_width,
|
|
source->uv_crop_height, in_bd, shift);
|
|
|
|
ssimv = a * .8 + .1 * (b + c);
|
|
|
|
*weight = 1;
|
|
|
|
return ssimv;
|
|
}
|
|
|
|
#endif // CONFIG_VP9_HIGHBITDEPTH
|