pdiff.cc.svn-base

SumatraPDF是一款小型开源的pdf阅读工具。虽然玲珑小巧（只有800多KB）

/*
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

Code from http://pdiff.svn.sourceforge.net
*/

#include "pdiff.h"
#include <math.h>
#include <stdio.h>

#ifndef M_PI
#define M_PI 3.14159265f
#endif

CompareArgs::CompareArgs()
{
    ImgA = NULL;
    ImgB = NULL;
    ImgDiff = NULL;
    FieldOfView = 45.0f;
    Gamma = 2.2f;
    Luminance = 100.0f;
}

CompareArgs::~CompareArgs()
{
    if (ImgA) delete ImgA;
    if (ImgB) delete ImgB;
    if (ImgDiff) delete ImgDiff;
}

#define MAX_PYR_LEVELS 8

class LPyramid
{
public:
    LPyramid(float *image, int width, int height);
    virtual ~LPyramid();
    float Get_Value(int x, int y, int level);
protected:
    float *Copy(float *img);
    void Convolve(float *a, float *b);

    // Succesively blurred versions of the original image
    float *Levels[MAX_PYR_LEVELS];

    int Width;
    int Height;
};

LPyramid::LPyramid(float *image, int width, int height) :
    Width(width),
    Height(height)
{
    // Make the Laplacian pyramid by successively
    // copying the earlier levels and blurring them
    for (int i=0; i<MAX_PYR_LEVELS; i++) {
        if (i == 0) {
            Levels[i] = Copy(image);
        } else {
            Levels[i] = new float[Width * Height];
            Convolve(Levels[i], Levels[i - 1]);
        }
    }
}

LPyramid::~LPyramid()
{
    for (int i=0; i<MAX_PYR_LEVELS; i++) {
        if (Levels[i]) delete Levels[i];
    }
}

float *LPyramid::Copy(float *img)
{
    int max = Width * Height;
    float *out = new float[max];
    for (int i = 0; i < max; i++) out[i] = img[i];

    return out;
}

void LPyramid::Convolve(float *a, float *b)
// convolves image b with the filter kernel and stores it in a
{
    int y,x,i,j,nx,ny;
    const float Kernel[] = {0.05f, 0.25f, 0.4f, 0.25f, 0.05f};

    for (y=0; y<Height; y++) {
        for (x=0; x<Width; x++) {
            int index = y * Width + x;
            a[index] = 0.0f;
            for (i=-2; i<=2; i++) {
                for (j=-2; j<=2; j++) {
                    nx=x+i;
                    ny=y+j;
                    if (nx<0) nx=-nx;
                    if (ny<0) ny=-ny;
                    if (nx>=Width) nx=2*(Width-1)-nx;
                    if (ny>=Height) ny=2*(Height-1)-ny;
                    a[index] += Kernel[i+2] * Kernel[j+2] * b[ny * Width + nx];
                } 
            }
        }
    }
}

float LPyramid::Get_Value(int x, int y, int level)
{
    int index = x + y * Width;
    int l = level;
    if (l > MAX_PYR_LEVELS) l = MAX_PYR_LEVELS;
    return Levels[level][index];
}

/*
* 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
*/ 

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)
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
*/
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
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;
}

void XYZToLAB(float x, float y, float z, float &L, float &A, float &B)
{
    static float xw = -1;
    static float yw;
    static float zw;
    // reference white
    if (xw < 0) {
    	AdobeRGBToXYZ(1, 1, 1, xw, yw, zw);
    }
    const float epsilon  = 216.0f / 24389.0f;
    const float kappa = 24389.0f / 27.0f;
    float f[3];
    float r[3];
    r[0] = x / xw;
    r[1] = y / yw;
    r[2] = z / zw;
    for (int 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]);
}

unsigned long Yee_Compare(CompareArgs &args)
{
    if ((args.ImgA->Get_Width() != args.ImgB->Get_Width()) ||
        (args.ImgA->Get_Height() != args.ImgB->Get_Height())) {
        return DIFFERENT_SIZES;
    }

    unsigned int i, dim;
    dim = args.ImgA->Get_Width() * args.ImgA->Get_Height();
    bool identical = true;
    for (i = 0; i < dim; i++) {
        if (args.ImgA->Get(i) != args.ImgB->Get(i)) {
          identical = false;
          break;
        }
    }
    if (identical) {
        return IDENTICAL;
    }

    // assuming colorspaces are in Adobe RGB (1998) convert to XYZ
    float *aX = new float[dim];
    float *aY = new float[dim];
    float *aZ = new float[dim];
    float *bX = new float[dim];
    float *bY = new float[dim];
    float *bZ = new float[dim];
    float *aLum = new float[dim];
    float *bLum = new float[dim];

    float *aA = new float[dim];
    float *bA = new float[dim];
    float *aB = new float[dim];
    float *bB = new float[dim];

    unsigned int x, y, w, h;
    w = args.ImgA->Get_Width();
    h = args.ImgA->Get_Height();
    for (y = 0; y < h; y++) {
        for (x = 0; x < w; x++) {
            float r, g, b, l;
            i = x + y * w;
            r = powf(args.ImgA->Get_Red(i) / 255.0f, args.Gamma);
            g = powf(args.ImgA->Get_Green(i) / 255.0f, args.Gamma);
            b = powf(args.ImgA->Get_Blue(i) / 255.0f, args.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(args.ImgB->Get_Red(i) / 255.0f, args.Gamma);
            g = powf(args.ImgB->Get_Green(i) / 255.0f, args.Gamma);
            b = powf(args.ImgB->Get_Blue(i) / 255.0f, args.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] * args.Luminance;
            bLum[i] = bY[i] * args.Luminance;
        }
    }

    LPyramid *la = new LPyramid(aLum, w, h);
    LPyramid *lb = new LPyramid(bLum, w, h);

    float num_one_degree_pixels = (float) (2 * tan( args.FieldOfView * 0.5 * M_PI / 180) * 180 / M_PI);
    float pixels_per_degree = w / num_one_degree_pixels;

    float num_pixels = 1;
    unsigned int 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;
    }

    float cpd[MAX_PYR_LEVELS];
    cpd[0] = 0.5f * pixels_per_degree;
    for (i = 1; i < MAX_PYR_LEVELS; i++) cpd[i] = 0.5f * cpd[i - 1];
    float csf_max = csf(3.248f, 100.0f);

    float F_freq[MAX_PYR_LEVELS - 2];
    for (i = 0; i < MAX_PYR_LEVELS - 2; i++) F_freq[i] = csf_max / csf( cpd[i], 100.0f);

    unsigned int 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 sum_contrast = 0;
            for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
                float n1 = fabsf(la->Get_Value(x,y,i) - la->Get_Value(x,y,i + 1));
                float n2 = fabsf(lb->Get_Value(x,y,i) - lb->Get_Value(x,y,i + 1));
                float numerator = (n1 > n2) ? n1 : n2;
                float d1 = fabsf(la->Get_Value(x,y,i+2));
                float d2 = fabsf(lb->Get_Value(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;
            float F_mask[MAX_PYR_LEVELS - 2];
            float adapt = la->Get_Value(x,y,adaptation_level) + lb->Get_Value(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)); 
            }
            float 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;
            float delta = fabsf(la->Get_Value(x,y,0) - lb->Get_Value(x,y,0));
            bool pass = true;
            // pure luminance test
            if (delta > factor * tvi(adapt)) {
                pass = false;
            } else {
                // CIE delta E test with modifications
                float color_scale = 1.0f;
                // 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;
                }
                float da = aA[index] - bA[index];
                float db = aB[index] - bB[index];
                da = da * da;
                db = db * db;
                float delta_e = (da + db) * color_scale;
                if (delta_e > factor) {
                    pass = false;
                }
            }
            if (!pass) {
                pixels_failed++;
                if (args.ImgDiff) {
                    args.ImgDiff->Set(255, 0, 0, 255, index);
                }
            } else {
                if (args.ImgDiff) {
                    args.ImgDiff->Set(0, 0, 0, 255, index);
                }
            }
        }
    }

    if (aX) delete[] aX;
    if (aY) delete[] aY;
    if (aZ) delete[] aZ;
    if (bX) delete[] bX;
    if (bY) delete[] bY;
    if (bZ) delete[] bZ;
    if (aLum) delete[] aLum;
    if (bLum) delete[] bLum;
    if (la) delete la;
    if (lb) delete lb;
    if (aA) delete aA;
    if (bA) delete bA;
    if (aB) delete aB;
    if (bB) delete bB;

    return (unsigned long)pixels_failed;

}