前言：之前在公司做專案的用到photoshop顏色空間的一些相關方法，在此總結一下。下面原理部分是從我的總結文件裡擷取來的。需要複製的童鞋自己手寫一下~

2、程式部分

1）Matlab實驗程式。

 1 clc;clear;close all;
 2 Image=imread('Fotor_LomoOrg.bmp');
 3 figure(1);
 4 imshow(Image);
 5  
 6 R=double(Image(:,:,1));
 7 G=double(Image(:,:,2));
 8 B=double(Image(:,:,3));
 9  
10 %調整引數
11 HighLight=238
 
;
12 Shadow=159;
13 Midtones=0.51;
14  
15 Diff=HighLight-Shadow;
16 rDiff=R-Shadow;
17 gDiff=G-Shadow;
18 bDiff=B-Shadow;
19  
20 rDiff(rDiff<0)=0;  
21 gDiff(gDiff<0)=0;  
22 bDiff(bDiff<0)=0;  
23  
24 R=(rDiff/Diff).^(1/Midtones)*255;
25 G=(gDiff/Diff).^(1/Midtones)*255;
26 B=(bDiff/Diff).^(1/Midtones)*255
 
;
27  
28 R(R>255)=255;
29 G(G>255)=255;
30 B(B>255)=255;
31  
32 img(:,:,1)=uint8(R);
33 img(:,:,2)=uint8(G);
34 img(:,:,3)=uint8(B);
35 figure(2);
36 imshow(img);
37 </span>

2）C程式

 1 void LevelAdjustRGB(unsigned char *pSrc, unsigned char *pDest, int nWidth, int nHeight,int nShadow,int
 
 nHighLight,double dMidtone)
 2 {
 3        //區域性變數宣告
 4     int i = 0; 
 5     int nLength  = nWidth * nHeight;
 6     double dDiff = nHighLight-nShadow;
 7     int *nRgbDiff = new int[3 * nLength];
 8  
 9     for(i = 0;i < 3 * nLength; i++)
10     {
11         nRgbDiff[i] = pSrc[i] - nShadow;
12         if(nRgbDiff[i] < 0)
13         {
14             nRgbDiff[i] = 0;
15         }
16  
17         //此處必須用int作為中間變數 不能用char  會有資料截斷
18         int nTemp = static_cast<int>(pow((nRgbDiff[i] / dDiff),1 / dMidtone) * 255);
19         pDest[i] = CLIP8(nTemp);
20     }
21     //釋放空間
22     if(!nRgbDiff)
23     {
24         delete []nRgbDiff;
25         nRgbDiff = NULL;
26     }
27 }</span>

其中

#define  CLIP8(a)  (((a) & 0xFFFFFF00) ? (((a) < 0) ? 0 : 255 ) : (a))      ///<判斷8位資料範圍

3、實驗結果，同photoshop處理結果

圖1 原圖

圖2 nShadow=159 nHighLight=238 dMidtone=0.51結果