前言：之前在公司做項目的用到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檔里截取來的。需要復制的童鞋自己手寫一下~
2、程序部分
1）Matlab實驗程序。
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 %調整參數 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程序
1 void LevelAdjustRGB(unsigned char *pSrc, unsigned char *pDest, int nWidth, int nHeight,int nShadow,int nHighLight,double dMidtone) 2 { 3 //局部變量聲明
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作為中間變量 不能用char 會有數據截斷
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位數據范圍
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