/*
Metric
Copyright (C) 2006 Yangli Hector Yee
This program is free software; you can redistribute it and/or modify it under the terms of the
GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program;
if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
*/
#define _GNU_SOURCE
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include "lpyramid.h"
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#if HAVE_STDINT_H
# include <stdint.h>
#elif HAVE_INTTYPES_H
# include <inttypes.h>
#elif HAVE_SYS_INT_TYPES_H
# include <sys/int_types.h>
#elif defined(_MSC_VER)
typedef __int8 int8_t;
typedef unsigned __int8 uint8_t;
typedef __int16 int16_t;
typedef unsigned __int16 uint16_t;
typedef __int32 int32_t;
typedef unsigned __int32 uint32_t;
typedef __int64 int64_t;
typedef unsigned __int64 uint64_t;
# ifndef HAVE_UINT64_T
# define HAVE_UINT64_T 1
# endif
# ifndef INT16_MIN
# define INT16_MIN (-32767-1)
# endif
# ifndef INT16_MAX
# define INT16_MAX (32767)
# endif
# ifndef UINT16_MAX
# define UINT16_MAX (65535)
# endif
#else
#error Cannot find definitions for fixed-width integral types (uint8_t, uint32_t, etc.)
#endif
#include "pdiff.h"
#ifndef M_PI
#define M_PI 3.14159265f
#endif
#ifndef __USE_ISOC99
#define expf exp
#define powf pow
#define fabsf fabs
#define sqrtf sqrt
#define log10f log10
#endif
/*
* Given the adaptation luminance, this function returns the
* threshold of visibility in cd per m^2
* TVI means Threshold vs Intensity function
* This version comes from Ward Larson Siggraph 1997
*/
static float
tvi (float adaptation_luminance)
{
/* returns the threshold luminance given the adaptation luminance
units are candelas per meter squared
*/
float log_a, r, result;
log_a = log10f(adaptation_luminance);
if (log_a < -3.94f) {
r = -2.86f;
} else if (log_a < -1.44f) {
r = powf(0.405f * log_a + 1.6f , 2.18f) - 2.86f;
} else if (log_a < -0.0184f) {
r = log_a - 0.395f;
} else if (log_a < 1.9f) {
r = powf(0.249f * log_a + 0.65f, 2.7f) - 0.72f;
} else {
r = log_a - 1.255f;
}
result = powf(10.0f , r);
return result;
}
/* computes the contrast sensitivity function (Barten SPIE 1989)
* given the cycles per degree (cpd) and luminance (lum)
*/
static float
csf (float cpd, float lum)
{
float a, b, result;
a = 440.0f * powf((1.0f + 0.7f / lum), -0.2f);
b = 0.3f * powf((1.0f + 100.0f / lum), 0.15f);
result = a * cpd * expf(-b * cpd) * sqrtf(1.0f + 0.06f * expf(b * cpd));
return result;
}
/*
* Visual Masking Function
* from Daly 1993
*/
static float
mask (float contrast)
{
float a, b, result;
a = powf(392.498f * contrast, 0.7f);
b = powf(0.0153f * a, 4.0f);
result = powf(1.0f + b, 0.25f);
return result;
}
/* convert Adobe RGB (1998) with reference white D65 to XYZ */
static void
AdobeRGBToXYZ (float r, float g, float b, float *x, float *y, float *z)
{
/* matrix is from http://www.brucelindbloom.com/ */
*x = r * 0.576700f + g * 0.185556f + b * 0.188212f;
*y = r * 0.297361f + g * 0.627355f + b * 0.0752847f;
*z = r * 0.0270328f + g * 0.0706879f + b * 0.991248f;
}
static void
XYZToLAB (float x, float y, float z, float *L, float *A, float *B)
{
static float xw = -1;
static float yw;
static float zw;
const float epsilon = 216.0f / 24389.0f;
const float kappa = 24389.0f / 27.0f;
float f[3];
float r[3];
int i;
/* reference white */
if (xw < 0) {
AdobeRGBToXYZ(1, 1, 1, &xw, &yw, &zw);
}
r[0] = x / xw;
r[1] = y / yw;
r[2] = z / zw;
for (i = 0; i < 3; i++) {
if (r[i] > epsilon) {
f[i] = powf(r[i], 1.0f / 3.0f);
} else {
f[i] = (kappa * r[i] + 16.0f) / 116.0f;
}
}
*L = 116.0f * f[1] - 16.0f;
*A = 500.0f * (f[0] - f[1]);
*B = 200.0f * (f[1] - f[2]);
}
static uint32_t
_get_pixel (const uint32_t *data, int i)
{
return data[i];
}
static unsigned char
_get_red (const uint32_t *data, int i)
{
uint32_t pixel;
uint8_t alpha;
pixel = _get_pixel (data, i);
alpha = (pixel & 0xff000000) >> 24;
if (alpha == 0)
return 0;
else
return (((pixel & 0x00ff0000) >> 16) * 255 + alpha / 2) / alpha;
}
static unsigned char
_get_green (const uint32_t *data, int i)
{
uint32_t pixel;
uint8_t alpha;
pixel = _get_pixel (data, i);
alpha = (pixel & 0xff000000) >> 24;
if (alpha == 0)
return 0;
else
return (((pixel & 0x0000ff00) >> 8) * 255 + alpha / 2) / alpha;
}
static unsigned char
_get_blue (const uint32_t *data, int i)
{
uint32_t pixel;
uint8_t alpha;
pixel = _get_pixel (data, i);
alpha = (pixel & 0xff000000) >> 24;
if (alpha == 0)
return 0;
else
return (((pixel & 0x000000ff) >> 0) * 255 + alpha / 2) / alpha;
}
static void *
xmalloc (size_t size)
{
void *buf;
buf = malloc (size);
if (buf == NULL) {
fprintf (stderr, "Out of memory.\n");
exit (1);
}
return buf;
}
int
pdiff_compare (cairo_surface_t *surface_a,
cairo_surface_t *surface_b,
double gamma,
double luminance,
double field_of_view)
{
unsigned int dim = (cairo_image_surface_get_width (surface_a)
* cairo_image_surface_get_height (surface_a));
unsigned int i;
/* assuming colorspaces are in Adobe RGB (1998) convert to XYZ */
float *aX;
float *aY;
float *aZ;
float *bX;
float *bY;
float *bZ;
float *aLum;
float *bLum;
float *aA;
float *bA;
float *aB;
float *bB;
unsigned int x, y, w, h;
lpyramid_t *la, *lb;
float num_one_degree_pixels, pixels_per_degree, num_pixels;
unsigned int adaptation_level;
float cpd[MAX_PYR_LEVELS];
float F_freq[MAX_PYR_LEVELS - 2];
float csf_max;
const uint32_t *data_a, *data_b;
unsigned int pixels_failed;
w = cairo_image_surface_get_width (surface_a);
h = cairo_image_surface_get_height (surface_a);
if (w < 3 || h < 3) /* too small for the Laplacian convolution */
return -1;
aX = xmalloc (dim * sizeof (float));
aY = xmalloc (dim * sizeof (float));
aZ = xmalloc (dim * sizeof (float));
bX = xmalloc (dim * sizeof (float));
bY = xmalloc (dim * sizeof (float));
bZ = xmalloc (dim * sizeof (float));
aLum = xmalloc (dim * sizeof (float));
bLum = xmalloc (dim * sizeof (float));
aA = xmalloc (dim * sizeof (float));
bA = xmalloc (dim * sizeof (float));
aB = xmalloc (dim * sizeof (float));
bB = xmalloc (dim * sizeof (float));
data_a = (uint32_t *) cairo_image_surface_get_data (surface_a);
data_b = (uint32_t *) cairo_image_surface_get_data (surface_b);
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++) {
float r, g, b, l;
i = x + y * w;
r = powf(_get_red (data_a, i) / 255.0f, gamma);
g = powf(_get_green (data_a, i) / 255.0f, gamma);
b = powf(_get_blue (data_a, i) / 255.0f, gamma);
AdobeRGBToXYZ(r,g,b,&aX[i],&aY[i],&aZ[i]);
XYZToLAB(aX[i], aY[i], aZ[i], &l, &aA[i], &aB[i]);
r = powf(_get_red (data_b, i) / 255.0f, gamma);
g = powf(_get_green (data_b, i) / 255.0f, gamma);
b = powf(_get_blue (data_b, i) / 255.0f, gamma);
AdobeRGBToXYZ(r,g,b,&bX[i],&bY[i],&bZ[i]);
XYZToLAB(bX[i], bY[i], bZ[i], &l, &bA[i], &bB[i]);
aLum[i] = aY[i] * luminance;
bLum[i] = bY[i] * luminance;
}
}
la = lpyramid_create (aLum, w, h);
lb = lpyramid_create (bLum, w, h);
num_one_degree_pixels = (float) (2 * tan(field_of_view * 0.5 * M_PI / 180) * 180 / M_PI);
pixels_per_degree = w / num_one_degree_pixels;
num_pixels = 1;
adaptation_level = 0;
for (i = 0; i < MAX_PYR_LEVELS; i++) {
adaptation_level = i;
if (num_pixels > num_one_degree_pixels) break;
num_pixels *= 2;
}
cpd[0] = 0.5f * pixels_per_degree;
for (i = 1; i < MAX_PYR_LEVELS; i++) cpd[i] = 0.5f * cpd[i - 1];
csf_max = csf(3.248f, 100.0f);
for (i = 0; i < MAX_PYR_LEVELS - 2; i++) F_freq[i] = csf_max / csf( cpd[i], 100.0f);
pixels_failed = 0;
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++) {
int index = x + y * w;
float contrast[MAX_PYR_LEVELS - 2];
float F_mask[MAX_PYR_LEVELS - 2];
float factor;
float delta;
float adapt;
bool pass;
float sum_contrast = 0;
for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
float n1 = fabsf(lpyramid_get_value (la,x,y,i) - lpyramid_get_value (la,x,y,i + 1));
float n2 = fabsf(lpyramid_get_value (lb,x,y,i) - lpyramid_get_value (lb,x,y,i + 1));
float numerator = (n1 > n2) ? n1 : n2;
float d1 = fabsf(lpyramid_get_value(la,x,y,i+2));
float d2 = fabsf(lpyramid_get_value(lb,x,y,i+2));
float denominator = (d1 > d2) ? d1 : d2;
if (denominator < 1e-5f) denominator = 1e-5f;
contrast[i] = numerator / denominator;
sum_contrast += contrast[i];
}
if (sum_contrast < 1e-5) sum_contrast = 1e-5f;
adapt = lpyramid_get_value(la,x,y,adaptation_level) + lpyramid_get_value(lb,x,y,adaptation_level);
adapt *= 0.5f;
if (adapt < 1e-5) adapt = 1e-5f;
for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
F_mask[i] = mask(contrast[i] * csf(cpd[i], adapt));
}
factor = 0;
for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
factor += contrast[i] * F_freq[i] * F_mask[i] / sum_contrast;
}
if (factor < 1) factor = 1;
if (factor > 10) factor = 10;
delta = fabsf(lpyramid_get_value(la,x,y,0) - lpyramid_get_value(lb,x,y,0));
pass = true;
/* pure luminance test */
if (delta > factor * tvi(adapt)) {
pass = false;
} else {
/* CIE delta E test with modifications */
float color_scale = 1.0f;
float da = aA[index] - bA[index];
float db = aB[index] - bB[index];
float delta_e;
/* ramp down the color test in scotopic regions */
if (adapt < 10.0f) {
color_scale = 1.0f - (10.0f - color_scale) / 10.0f;
color_scale = color_scale * color_scale;
}
da = da * da;
db = db * db;
delta_e = (da + db) * color_scale;
if (delta_e > factor) {
pass = false;
}
}
if (!pass)
pixels_failed++;
}
}
free (aX);
free (aY);
free (aZ);
free (bX);
free (bY);
free (bZ);
free (aLum);
free (bLum);
lpyramid_destroy (la);
lpyramid_destroy (lb);
free (aA);
free (bA);
free (aB);
free (bB);
return pixels_failed;
}