Photoshop图像处理算法—饱和度调整

前言：之前在公司做项目的用到photoshop颜色空间的一些相关方法，在此总结一下。下面原理部分是从我的总结文档里截取来的。需要复制的童鞋自己手写一下~

2、程序部分

1）Matlab实验程序。

span style="font-size:18px;"clc;clear all;close all;

Image=imread('Fotor_LomoOrg.bmp');

Image=double(Image);

R=Image(:,:,1);

G=Image(:,:,2);

B=Image(:,:,*);

[row, col] = size(R);

R_new=R;

G_new=G;

B_new=B;

%%%% Increment, 饱和度调整增量（-100,100）photoshop的范围

Increment=-*0;

%换算成调整比率

Increment=Increment/100;

%利用HSL模式求得颜色的S和L

for i=1:row

for j=1:col

rgbMax=max(R(i,j),max(G(i,j),B(i,j)));

rgbMin=min(R(i,j),min(G(i,j),B(i,j)));

Delta=(rgbMax-rgbMin)/2**;

if(Delta==0) %如果delta=0，则饱和度S=0，所以不能调整饱和度

continue;

end

value = (rgbMax + rgbMin)/2**;

L=value/2; %Lightness

if(L0.*) %根据明度L计算饱和度S

S=Delta/value;

else

S =Delta/(2 - value);

end

%具体的饱和度调整，Increment为饱和度增减量

if (Increment=0)

if((Increment+S)=1)

alpha=S;

else

alpha=1-Increment;

end

alpha=1/alpha-1;

R_new(i,j) = R(i,j) + (R(i,j) - L * 2**) * alpha;

G_new(i,j) = G(i,j) + (G(i,j) - L * 2**) * alpha;

B_new(i,j) = B(i,j) + (B(i,j) - L * 2**) * alpha;

else

alpha=Increment;

R_new(i,j) = L*2** + (R(i,j) - L * 2**) * (1+alpha);

G_new(i,j) = L*2** + (G(i,j) - L * 2**) * (1+alpha);

B_new(i,j) = L*2** + (B(i,j) - L * 2**) * (1+alpha);

end

end

end

Image_new(:,:,1)=R_new;

Image_new(:,:,2)=G_new;

Image_new(:,:,*)=B_new;

imshow(Image/2**);

figure, imshow(Image_new/2**);/spanspan style="font-weight: bold; font-size: 18px;"

/span

2）C程序，此处只贴上关键处理部分，已经把图像变成了数组来处理

span style="font-size:18px;"void SaturationAdjustRGB(unsigned char *pSrc, unsigned char *pDest, int nWidth, int nHeight,int nParameter)

//局部变量声明

int i = 0;

int t = 0;

int nLength = nHeight * nWidth;

//参数处理

double dPercent= static_cast double (nParameter) / 100;

//RGB颜色通道声明

unsigned char *imgR = new unsigned char[nLength];

unsigned char *imgG = new unsigned char[nLength];

unsigned char *imgB = new unsigned char[nLength];

//局部变量声明

unsigned char rgbMax;

unsigned char rgbMin;

double dDelta;

double dValue;

double dL;

double dS;

double dAlpha;

//分离出RGB通道

for (i = 0; i nLength; i++)

t = * * i;

imgB[i] = pSrc[t];

imgG[i] = pSrc[t + 1];

imgR[i] = pSrc[t + 2];

for (int i = 0; i nLength; i++)

rgbMax = max(max(imgR[i] , imgG[i]) , imgB[i]);

rgbMin = min(min(imgR[i] , imgG[i]) , imgB[i]);

dDelta = static_castdouble(rgbMax - rgbMin) / 2**;

dValue = static_castdouble(rgbMax + rgbMin) / 2**;

//如果该像素点是灰色 不处理

if(0 == dDelta)

continue;

//按照公式计算明度L [0,1]

dL = dValue / 2;

//按照公式计算饱和度S [0,1]

if(dL 0.*)

dS = dDelta / dValue;

else

dS = dDelta / (2 - dValue);

//进行饱和度调整

if(dPercent = 0)

if(dPercent + dS = 1)

dAlpha = dS;

else

dAlpha = 1 - dPercent;

dAlpha = 1 / dAlpha - 1;

imgB[i] = imgB[i] + (imgB[i] - dL * 2**) * dAlpha;

imgG[i] = imgG[i] + (imgG[i] - dL * 2**) * dAlpha;

imgR[i] = imgR[i] + (imgR[i] - dL * 2**) * dAlpha;

else

dAlpha = dPercent;

imgB[i] = dL * 2** + (imgB[i] - dL * 2**) * (1 + dAlpha);

imgG[i] = dL * 2** + (imgG[i] - dL * 2**) * (1 + dAlpha);

imgR[i] = dL * 2** + (imgR[i] - dL * 2**) * (1 + dAlpha);

//得到结果

for(i = 0; i nLength; i++)

t = * * i;

pDest[t] = imgB[i];

pDest[t + 1] = imgG[i];

pDest[t + 2] = imgR[i];

//释放内存

if(!imgR)

delete []imgR;

imgR = NULL;

if(!imgG)

delete []imgG;

imgG = NULL;

if(!imgB)

delete []imgB;

imgB = NULL;

}/span

*、实验结果，与photoshop处理结果一致

图1 原图

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