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get_disto: new option to compute SSIM map and convert to gray

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using -ssim -o will trigger SSIM map calculation instead of add-diff map.

-gray converts the error map to intensity instead of having each channels' error separated.

Change-Id: I4bdb88880a252e5562aa4e0e3c2353ad93aef20e
This commit is contained in:
Pascal Massimino 2016-09-27 14:20:21 +02:00
parent 86a84b3598
commit 36aa087b6d
1 changed files with 147 additions and 19 deletions
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166
extras/get_disto.c
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@ -12,12 +12,13 @@
//
/*
gcc -o get_disto get_disto.c -O3 -I../ -L../examples -L../imageio \
-lexample_util -limagedec -lwebp -L/opt/local/lib \
-lexample_util -limageio_util -limagedec -lwebp -L/opt/local/lib \
-lpng -lz -ljpeg -ltiff -lm -lpthread
*/
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -47,35 +48,154 @@ static size_t ReadPicture(const char* const filename, WebPPicture* const pic,
return ok ? data_size : 0;
}
// returns the max absolute difference
static void RescalePlane(uint8_t* plane, int width, int height,
int x_stride, int y_stride, int max) {
const uint32_t factor = (max > 0) ? (255u << 16) / max : 0;
int x, y;
for (y = 0; y < height; ++y) {
uint8_t* const ptr = plane + y * y_stride;
for (x = 0; x < width * x_stride; x += x_stride) {
const uint32_t diff = (ptr[x] * factor + (1 << 15)) >> 16;
ptr[x] = diff;
}
}
}
// Return the max absolute difference.
static int DiffScaleChannel(uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
int x_stride, int w, int h, int do_scaling) {
int x, y;
uint32_t max = 1;
int max = 0;
for (y = 0; y < h; ++y) {
uint8_t* const ptr1 = src1 + y * stride1;
const uint8_t* const ptr2 = src2 + y * stride2;
for (x = 0; x < w * x_stride; x += x_stride) {
const uint32_t diff = abs(ptr1[x] - ptr2[x]);
const int diff = abs(ptr1[x] - ptr2[x]);
if (diff > max) max = diff;
ptr1[x] = diff;
}
}
if (do_scaling) {
const uint32_t factor = (255u << 16) / max;
for (y = 0; y < h; ++y) {
uint8_t* const ptr1 = src1 + y * stride1;
for (x = 0; x < w * x_stride; x += x_stride) {
const uint32_t diff = (ptr1[x] * factor) >> 16;
ptr1[x] = diff;
}
if (do_scaling) RescalePlane(src1, w, h, x_stride, stride1, max);
return max;
}
//------------------------------------------------------------------------------
// SSIM calculation. We re-implement these functions here, out of dsp/, to avoid
// breaking the library's hidden visibility. This code duplication avoids the
// bigger annoyance of having to open up internal details of libdsp...
#define SSIM_KERNEL 3 // total size of the kernel: 2 * SSIM_KERNEL + 1
// struct for accumulating statistical moments
typedef struct {
uint32_t w; // sum(w_i) : sum of weights
uint32_t xm, ym; // sum(w_i * x_i), sum(w_i * y_i)
uint32_t xxm, xym, yym; // sum(w_i * x_i * x_i), etc.
} DistoStats;
static const double kMinValue = 1.e-10; // minimal threshold
static WEBP_INLINE double SSIMCalculation(const DistoStats* const stats) {
const uint32_t N = stats->w;
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;
}
static double SSIMGetClipped(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
int xo, int yo, int W, int H) {
DistoStats stats = { 0, 0, 0, 0, 0, 0 };
const int ymin = (yo - SSIM_KERNEL < 0) ? 0 : yo - SSIM_KERNEL;
const int ymax = (yo + SSIM_KERNEL > H - 1) ? H - 1 : yo + SSIM_KERNEL;
const int xmin = (xo - SSIM_KERNEL < 0) ? 0 : xo - SSIM_KERNEL;
const int xmax = (xo + SSIM_KERNEL > W - 1) ? W - 1 : xo + SSIM_KERNEL;
int x, y;
src1 += ymin * stride1;
src2 += ymin * stride2;
for (y = ymin; y <= ymax; ++y, src1 += stride1, src2 += stride2) {
for (x = xmin; x <= xmax; ++x) {
const int s1 = src1[x];
const int s2 = src2[x];
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 SSIMCalculation(&stats);
}
// Compute SSIM-score map. Return -1 in case of error, max diff otherwise.
static int SSIMScaleChannel(uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
int x_stride, int w, int h, int do_scaling) {
int x, y;
int max = 0;
uint8_t* const plane1 = (uint8_t*)malloc(2 * w * h * sizeof(*plane1));
uint8_t* const plane2 = plane1 + w * h;
if (plane1 == NULL) return -1;
// extract plane
for (y = 0; y < h; ++y) {
for (x = 0; x < w; ++x) {
plane1[x + y * w] = src1[x * x_stride + y * stride1];
plane2[x + y * w] = src2[x * x_stride + y * stride2];
}
}
for (y = 0; y < h; ++y) {
for (x = 0; x < w; ++x) {
const double ssim = SSIMGetClipped(plane1, w, plane2, w, x, y, w, h);
int diff = (int)(255 * (1. - ssim));
if (diff < 0) {
diff = 0;
} else if (diff > max) {
max = diff;
}
src1[x * x_stride + y * stride1] = (diff > 255) ? 255u : (uint8_t)diff;
}
}
free(plane1);
if (do_scaling) RescalePlane(src1, w, h, x_stride, stride1, max);
return max;
}
// Convert an argb picture to luminance.
static void ConvertToGray(WebPPicture* const pic) {
int x, y;
assert(pic != NULL);
assert(pic->use_argb);
for (y = 0; y < pic->height; ++y) {
uint32_t* const row = &pic->argb[y * pic->argb_stride];
for (x = 0; x < pic->width; ++x) {
const uint32_t argb = row[x];
const uint32_t r = (argb >> 0) & 0xff;
const uint32_t g = (argb >> 8) & 0xff;
const uint32_t b = (argb >> 16) & 0xff;
// We use BT.709 for converting to luminance.
const uint32_t Y = (uint32_t)(0.2126 * r + 0.7152 * g + 0.0722 * b + .5);
row[x] = (argb & 0xff000000u) | (Y * 0x010101u);
}
}
}
static void Help(void) {
fprintf(stderr,
"Usage: get_disto [-ssim][-psnr][-alpha] compressed.webp orig.webp\n"
@ -85,6 +205,7 @@ static void Help(void) {
" -h ........ this message\n"
" -o <file> . save the diff map as a WebP lossless file\n"
" -scale .... scale the difference map to fit [0..255] range\n"
" -gray ..... use grayscale for difference map (-scale)\n"
" Also handles PNG, JPG and TIFF files, in addition to WebP.\n");
}
@ -98,6 +219,7 @@ int main(int argc, const char *argv[]) {
int help = 0;
int keep_alpha = 0;
int scale = 0;
int use_gray = 0;
const char* name1 = NULL;
const char* name2 = NULL;
const char* output = NULL;
@ -116,6 +238,8 @@ int main(int argc, const char *argv[]) {
keep_alpha = 1;
} else if (!strcmp(argv[c], "-scale")) {
scale = 1;
} else if (!strcmp(argv[c], "-gray")) {
use_gray = 1;
} else if (!strcmp(argv[c], "-h")) {
help = 1;
ret = 0;
@ -160,23 +284,27 @@ int main(int argc, const char *argv[]) {
if (output != NULL) {
uint8_t* data = NULL;
size_t data_size = 0;
if (pic1.use_argb != pic1.use_argb) {
if (pic1.use_argb != pic2.use_argb) {
fprintf(stderr, "Pictures are not in the same argb format. "
"Can't save the difference map.\n");
goto End;
}
if (pic1.use_argb) {
int n;
fprintf(stderr, "max absolute differences per channel: ");
fprintf(stderr, "max differences per channel: ");
for (n = 0; n < 3; ++n) { // skip the alpha channel
const int range = DiffScaleChannel((uint8_t*)pic1.argb + n,
pic1.argb_stride * 4,
(const uint8_t*)pic2.argb + n,
pic2.argb_stride * 4,
4, pic1.width, pic1.height, scale);
const int range = (type == 1) ?
SSIMScaleChannel((uint8_t*)pic1.argb + n, pic1.argb_stride * 4,
(const uint8_t*)pic2.argb + n, pic2.argb_stride * 4,
4, pic1.width, pic1.height, scale) :
DiffScaleChannel((uint8_t*)pic1.argb + n, pic1.argb_stride * 4,
(const uint8_t*)pic2.argb + n, pic2.argb_stride * 4,
4, pic1.width, pic1.height, scale);
if (range < 0) fprintf(stderr, "\nError computing diff map\n");
fprintf(stderr, "[%d]", range);
}
fprintf(stderr, "\n");
if (use_gray) ConvertToGray(&pic1);
} else {
fprintf(stderr, "Can only compute the difference map in ARGB format.\n");
goto End;