# 跟进：找到颜色之间准确的“距离”Followup: Finding an accurate “distance” between colors

1. 什么颜色空间最能代表人类的视觉？
2. 该空间中的距离度量最能代表人类视觉（欧几里德？）

## 8 个回复8

### ===============>>#1 票数：43 已采纳

（L1-L2）^ 2 +（a1-a2）^ 2 +（b1-b2）^ 2

`a``b`值以类似于锥体的工作方式表示相反的颜色，并且可以是负的或正的。 中性色 - 白色，灰色是`a=0``b=0` `L`是以特定方式定义的亮度，从零（纯黑暗）到任何方式。

### ===============>>#2 票数：8

``````#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/photo/photo.hpp>
#include <math.h>

using namespace cv;
using namespace std;

#define REF_X 95.047; // Observer= 2°, Illuminant= D65
#define REF_Y 100.000;
#define REF_Z 108.883;

void bgr2xyz( const Vec3b& BGR, Vec3d& XYZ );
void xyz2lab( const Vec3d& XYZ, Vec3d& Lab );
void lab2lch( const Vec3d& Lab, Vec3d& LCH );
double deltaE2000( const Vec3b& bgr1, const Vec3b& bgr2 );
double deltaE2000( const Vec3d& lch1, const Vec3d& lch2 );

void bgr2xyz( const Vec3b& BGR, Vec3d& XYZ )
{
double r = (double)BGR[2] / 255.0;
double g = (double)BGR[1] / 255.0;
double b = (double)BGR[0] / 255.0;
if( r > 0.04045 )
r = pow( ( r + 0.055 ) / 1.055, 2.4 );
else
r = r / 12.92;
if( g > 0.04045 )
g = pow( ( g + 0.055 ) / 1.055, 2.4 );
else
g = g / 12.92;
if( b > 0.04045 )
b = pow( ( b + 0.055 ) / 1.055, 2.4 );
else
b = b / 12.92;
r *= 100.0;
g *= 100.0;
b *= 100.0;
XYZ[0] = r * 0.4124 + g * 0.3576 + b * 0.1805;
XYZ[1] = r * 0.2126 + g * 0.7152 + b * 0.0722;
XYZ[2] = r * 0.0193 + g * 0.1192 + b * 0.9505;
}

void xyz2lab( const Vec3d& XYZ, Vec3d& Lab )
{
double x = XYZ[0] / REF_X;
double y = XYZ[1] / REF_X;
double z = XYZ[2] / REF_X;
if( x > 0.008856 )
x = pow( x , .3333333333 );
else
x = ( 7.787 * x ) + ( 16.0 / 116.0 );
if( y > 0.008856 )
y = pow( y , .3333333333 );
else
y = ( 7.787 * y ) + ( 16.0 / 116.0 );
if( z > 0.008856 )
z = pow( z , .3333333333 );
else
z = ( 7.787 * z ) + ( 16.0 / 116.0 );
Lab[0] = ( 116.0 * y ) - 16.0;
Lab[1] = 500.0 * ( x - y );
Lab[2] = 200.0 * ( y - z );
}

void lab2lch( const Vec3d& Lab, Vec3d& LCH )
{
LCH[0] = Lab[0];
LCH[1] = sqrt( ( Lab[1] * Lab[1] ) + ( Lab[2] * Lab[2] ) );
LCH[2] = atan2( Lab[2], Lab[1] );
}

double deltaE2000( const Vec3b& bgr1, const Vec3b& bgr2 )
{
Vec3d xyz1, xyz2, lab1, lab2, lch1, lch2;
bgr2xyz( bgr1, xyz1 );
bgr2xyz( bgr2, xyz2 );
xyz2lab( xyz1, lab1 );
xyz2lab( xyz2, lab2 );
lab2lch( lab1, lch1 );
lab2lch( lab2, lch2 );
return deltaE2000( lch1, lch2 );
}

double deltaE2000( const Vec3d& lch1, const Vec3d& lch2 )
{
double avg_L = ( lch1[0] + lch2[0] ) * 0.5;
double delta_L = lch2[0] - lch1[0];
double avg_C = ( lch1[1] + lch2[1] ) * 0.5;
double delta_C = lch1[1] - lch2[1];
double avg_H = ( lch1[2] + lch2[2] ) * 0.5;
if( fabs( lch1[2] - lch2[2] ) > CV_PI )
avg_H += CV_PI;
double delta_H = lch2[2] - lch1[2];
if( fabs( delta_H ) > CV_PI )
{
if( lch2[2] <= lch1[2] )
delta_H += CV_PI * 2.0;
else
delta_H -= CV_PI * 2.0;
}

delta_H = sqrt( lch1[1] * lch2[1] ) * sin( delta_H ) * 2.0;
double T = 1.0 -
0.17 * cos( avg_H - CV_PI / 6.0 ) +
0.24 * cos( avg_H * 2.0 ) +
0.32 * cos( avg_H * 3.0 + CV_PI / 30.0 ) -
0.20 * cos( avg_H * 4.0 - CV_PI * 7.0 / 20.0 );
double SL = avg_L - 50.0;
SL *= SL;
SL = SL * 0.015 / sqrt( SL + 20.0 ) + 1.0;
double SC = avg_C * 0.045 + 1.0;
double SH = avg_C * T * 0.015 + 1.0;
double delta_Theta = avg_H / 25.0 - CV_PI * 11.0 / 180.0;
delta_Theta = exp( delta_Theta * -delta_Theta ) * ( CV_PI / 6.0 );
double RT = pow( avg_C, 7.0 );
RT = sqrt( RT / ( RT + 6103515625.0 ) ) * sin( delta_Theta ) * -2.0; // 6103515625 = 25^7
delta_L /= SL;
delta_C /= SC;
delta_H /= SH;
return sqrt( delta_L * delta_L + delta_C * delta_C + delta_H * delta_H + RT * delta_C * delta_H );
}
``````

### ===============>>#3 票数：4

HSL和HSV对人类的颜色感知更好。 根据维基百科

### ===============>>#6 票数：2

ImageMagic提供以下比例：

• 红色：0.3
• 绿色：0.6
• 蓝色：0.1