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speed-up SSIM calculation

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SSIM results are incompatible with previous version!
We're now averaging the SSIM value for each pixels instead of
printing a frame-level global SSIM value.

* Got rid of some old code
* switched to uint32_t for accumulation
* refactoring

SSIM calculation is ~4x faster now.

Change-Id: I48d838e66aef5199b9b5cd5cddef6a98411f5673
This commit is contained in:
Pascal Massimino
2016-09-14 16:15:43 +02:00
parent 64577de8ae
commit bfff0bf329
5 changed files with 143 additions and 201 deletions
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82
src/dsp/enc.c
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@ -693,10 +693,41 @@ static void Copy16x8(const uint8_t* src, uint8_t* dst) {
//------------------------------------------------------------------------------
// SSIM / PSNR
static void SSIMAccumulateClipped(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
int xo, int yo, int W, int H,
VP8DistoStats* const stats) {
static const double kMinValue = 1.e-10; // minimal threshold
static WEBP_INLINE double SSIMCalculation(
const VP8DistoStats* const stats, uint32_t N /*num samples*/) {
const double w2 = N * N;
const double C1 = 6.5025 * w2;
const double C2 = 58.5225 * w2;
const double xmxm = stats->xm * stats->xm;
const double ymym = stats->ym * stats->ym;
const double xmym = stats->xm * stats->ym;
const double sxy = stats->xym * N - xmym;
const double fnum = (2 * xmym + C1) * (2 * sxy + C2);
double fden;
double sxx = stats->xxm * N - xmxm;
double syy = stats->yym * N - ymym;
// small errors are possible, due to rounding. Clamp to zero.
if (sxx < 0.) sxx = 0.;
if (syy < 0.) syy = 0.;
fden = (xmxm + ymym + C1) * (sxx + syy + C2);
return (fden != 0.) ? fnum / fden : kMinValue;
}
double VP8SSIMFromStats(const VP8DistoStats* const stats) {
const uint32_t w = (2 * VP8_SSIM_KERNEL + 1) * (2 * VP8_SSIM_KERNEL + 1);
return SSIMCalculation(stats, w);
}
double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats) {
return SSIMCalculation(stats, stats->w);
}
static double SSIMGetClipped_C(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
int xo, int yo, int W, int H) {
VP8DistoStats stats = { 0., 0., 0., 0., 0., 0. };
const int ymin = (yo - VP8_SSIM_KERNEL < 0) ? 0 : yo - VP8_SSIM_KERNEL;
const int ymax = (yo + VP8_SSIM_KERNEL > H - 1) ? H - 1
: yo + VP8_SSIM_KERNEL;
@ -710,34 +741,37 @@ static void SSIMAccumulateClipped(const uint8_t* src1, int stride1,
for (x = xmin; x <= xmax; ++x) {
const int s1 = src1[x];
const int s2 = src2[x];
stats->w += 1;
stats->xm += s1;
stats->ym += s2;
stats->xxm += s1 * s1;
stats->xym += s1 * s2;
stats->yym += s2 * s2;
stats.xm += s1;
stats.ym += s2;
stats.xxm += s1 * s1;
stats.xym += s1 * s2;
stats.yym += s2 * s2;
}
}
stats.w = (ymax - ymin + 1) * (xmax - xmin + 1);
return VP8SSIMFromStatsClipped(&stats);
}
static void SSIMAccumulate(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
VP8DistoStats* const stats) {
static double SSIMGet_C(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2) {
VP8DistoStats stats = { 0., 0., 0., 0., 0., 0. };
int x, y;
for (y = 0; y <= 2 * VP8_SSIM_KERNEL; ++y, src1 += stride1, src2 += stride2) {
for (x = 0; x <= 2 * VP8_SSIM_KERNEL; ++x) {
const int s1 = src1[x];
const int s2 = src2[x];
stats->w += 1;
stats->xm += s1;
stats->ym += s2;
stats->xxm += s1 * s1;
stats->xym += s1 * s2;
stats->yym += s2 * s2;
stats.xm += s1;
stats.ym += s2;
stats.xxm += s1 * s1;
stats.xym += s1 * s2;
stats.yym += s2 * s2;
}
}
return VP8SSIMFromStats(&stats);
}
//------------------------------------------------------------------------------
static uint32_t AccumulateSSE(const uint8_t* src1,
const uint8_t* src2, int len) {
int i;
@ -750,8 +784,10 @@ static uint32_t AccumulateSSE(const uint8_t* src1,
return sse2;
}
VP8SSIMAccumulateFunc VP8SSIMAccumulate;
VP8SSIMAccumulateClippedFunc VP8SSIMAccumulateClipped;
//------------------------------------------------------------------------------
VP8SSIMGetFunc VP8SSIMGet;
VP8SSIMGetClippedFunc VP8SSIMGetClipped;
VP8AccumulateSSEFunc VP8AccumulateSSE;
extern void VP8SSIMDspInitSSE2(void);
@ -762,8 +798,8 @@ static volatile VP8CPUInfo ssim_last_cpuinfo_used =
WEBP_TSAN_IGNORE_FUNCTION void VP8SSIMDspInit(void) {
if (ssim_last_cpuinfo_used == VP8GetCPUInfo) return;
VP8SSIMAccumulate = SSIMAccumulate;
VP8SSIMAccumulateClipped = SSIMAccumulateClipped;
VP8SSIMGetClipped = SSIMGetClipped_C;
VP8SSIMGet = SSIMGet_C;
VP8AccumulateSSE = AccumulateSSE;
if (VP8GetCPUInfo != NULL) {