iOS --- 經過CPU實現的簡單濾鏡效果

iOS中使用CPU實現濾鏡效果的原理很簡單, 即將圖片轉換成像素數據, 而後對每個像素進行相應的濾鏡效果計算, 而後從新獲得過濾後的圖片.
CPU濾鏡效果代碼以下:

頭文件

//  CPUImageFilterUtil.h

#import 
#import 
#import 
#import 

//LOMO
static const float colormatrix_lomo[] = {
  1.7f,  0.1f, 0.1f, 0, -73.1f,
  0,  1.7f, 0.1f, 0, -73.1f,
  0,  0.1f, 1.6f, 0, -73.1f,
  0,  0, 0, 1.0f, 0 };

//黑白
static const float colormatrix_heibai[] = {
  0.8f,  1.6f, 0.2f, 0, -163.9f,
  0.8f,  1.6f, 0.2f, 0, -163.9f,
  0.8f,  1.6f, 0.2f, 0, -163.9f,
  0,  0, 0, 1.0f, 0 };
//復古
static const float colormatrix_huajiu[] = {
  0.2f,0.5f, 0.1f, 0, 40.8f,
  0.2f, 0.5f, 0.1f, 0, 40.8f,
  0.2f,0.5f, 0.1f, 0, 40.8f,
  0, 0, 0, 1, 0 };

//哥特
static const float colormatrix_gete[] = {
  1.9f,-0.3f, -0.2f, 0,-87.0f,
  -0.2f, 1.7f, -0.1f, 0, -87.0f,
  -0.1f,-0.6f, 2.0f, 0, -87.0f,
  0, 0, 0, 1.0f, 0 };

//銳化
static const float colormatrix_ruise[] = {
  4.8f,-1.0f, -0.1f, 0,-388.4f,
  -0.5f,4.4f, -0.1f, 0,-388.4f,
  -0.5f,-1.0f, 5.2f, 0,-388.4f,
  0, 0, 0, 1.0f, 0 };


//淡雅
static const float colormatrix_danya[] = {
  0.6f,0.3f, 0.1f, 0,73.3f,
  0.2f,0.7f, 0.1f, 0,73.3f,
  0.2f,0.3f, 0.4f, 0,73.3f,
  0, 0, 0, 1.0f, 0 };

//酒紅
static const float colormatrix_jiuhong[] = {
  1.2f,0.0f, 0.0f, 0.0f,0.0f,
  0.0f,0.9f, 0.0f, 0.0f,0.0f,
  0.0f,0.0f, 0.8f, 0.0f,0.0f,
  0, 0, 0, 1.0f, 0 };

//清寧
static const float colormatrix_qingning[] = {
  0.9f, 0, 0, 0, 0,
  0, 1.1f,0, 0, 0,
  0, 0, 0.9f, 0, 0,
  0, 0, 0, 1.0f, 0 };

//浪漫
static const float colormatrix_langman[] = {
  0.9f, 0, 0, 0, 63.0f,
  0, 0.9f,0, 0, 63.0f,
  0, 0, 0.9f, 0, 63.0f,
  0, 0, 0, 1.0f, 0 };

//光暈
static const float colormatrix_guangyun[] = {
  0.9f, 0, 0,  0, 64.9f,
  0, 0.9f,0,  0, 64.9f,
  0, 0, 0.9f,  0, 64.9f,
  0, 0, 0, 1.0f, 0 };

//藍調
static const float colormatrix_landiao[] = {
  2.1f, -1.4f, 0.6f, 0.0f, -31.0f,
  -0.3f, 2.0f, -0.3f, 0.0f, -31.0f,
  -1.1f, -0.2f, 2.6f, 0.0f, -31.0f,
  0.0f, 0.0f, 0.0f, 1.0f, 0.0f
};

//夢幻
static const float colormatrix_menghuan[] = {
  0.8f, 0.3f, 0.1f, 0.0f, 46.5f,
  0.1f, 0.9f, 0.0f, 0.0f, 46.5f,
  0.1f, 0.3f, 0.7f, 0.0f, 46.5f,
  0.0f, 0.0f, 0.0f, 1.0f, 0.0f
};

//夜色
static const float colormatrix_yese[] = {
  1.0f, 0.0f, 0.0f, 0.0f, -66.6f,
  0.0f, 1.1f, 0.0f, 0.0f, -66.6f,
  0.0f, 0.0f, 1.0f, 0.0f, -66.6f,
  0.0f, 0.0f, 0.0f, 1.0f, 0.0f
};

static const float colormatrixs[][20]={
  {
    0.8f,  1.6f, 0.2f, 0, -163.9f,
    0.8f,  1.6f, 0.2f, 0, -163.9f,
    0.8f,  1.6f, 0.2f, 0, -163.9f,
    0,  0, 0, 1.0f, 0
  },
  {
    0.2f,0.5f, 0.1f, 0, 40.8f,
    0.2f, 0.5f, 0.1f, 0, 40.8f,
    0.2f,0.5f, 0.1f, 0, 40.8f,
    0, 0, 0, 1, 0
  },
  {
    1.9f,-0.3f, -0.2f, 0,-87.0f,
    -0.2f, 1.7f, -0.1f, 0, -87.0f,
    -0.1f,-0.6f, 2.0f, 0, -87.0f,
    0, 0, 0, 1.0f, 0
  },
  {
    4.8f,-1.0f, -0.1f, 0,-388.4f,
    -0.5f,4.4f, -0.1f, 0,-388.4f,
    -0.5f,-1.0f, 5.2f, 0,-388.4f,
    0, 0, 0, 1.0f, 0
  },
  {
    0.6f,0.3f, 0.1f, 0,73.3f,
    0.2f,0.7f, 0.1f, 0,73.3f,
    0.2f,0.3f, 0.4f, 0,73.3f,
    0, 0, 0, 1.0f, 0
  },
  {
    1.2f,0.0f, 0.0f, 0.0f,0.0f,
    0.0f,0.9f, 0.0f, 0.0f,0.0f,
    0.0f,0.0f, 0.8f, 0.0f,0.0f,
    0, 0, 0, 1.0f, 0
  },
  {
    0.9f, 0, 0, 0, 0,
    0, 1.1f,0, 0, 0,
    0, 0, 0.9f, 0, 0,
    0, 0, 0, 1.0f, 0
  },
  {
    0.9f, 0, 0, 0, 63.0f,
    0, 0.9f,0, 0, 63.0f,
    0, 0, 0.9f, 0, 63.0f,
    0, 0, 0, 1.0f, 0
  },
  {
    0.9f, 0, 0,  0, 64.9f,
    0, 0.9f,0,  0, 64.9f,
    0, 0, 0.9f,  0, 64.9f,
    0, 0, 0, 1.0f, 0
  },
  {
    2.1f, -1.4f, 0.6f, 0.0f, -31.0f,
    -0.3f, 2.0f, -0.3f, 0.0f, -31.0f,
    -1.1f, -0.2f, 2.6f, 0.0f, -31.0f,
    0.0f, 0.0f, 0.0f, 1.0f, 0.0f
  },
  {
    0.8f, 0.3f, 0.1f, 0.0f, 46.5f,
    0.1f, 0.9f, 0.0f, 0.0f, 46.5f,
    0.1f, 0.3f, 0.7f, 0.0f, 46.5f,
    0.0f, 0.0f, 0.0f, 1.0f, 0.0f
  },
  {
    1.0f, 0.0f, 0.0f, 0.0f, -66.6f,
    0.0f, 1.1f, 0.0f, 0.0f, -66.6f,
    0.0f, 0.0f, 1.0f, 0.0f, -66.6f,
    0.0f, 0.0f, 0.0f, 1.0f, 0.0f
  }
};

@interface CPUImageFilterUtil : NSObject

+ (UIImage *)imageWithImage:(UIImage *)inImage withColorMatrix:(const float*)f;

@end

實現文件

//  CPUImageFilterUtil.m

#import CPUImageFilterUtil.h

@implementation CPUImageFilterUtil

// 返回一個使用RGBA通道的位圖上下文
static CGContextRef CreateRGBABitmapContext (CGImageRef inImage)
{
  CGContextRef context = NULL;
  CGColorSpaceRef colorSpace;

  //內存空間的指針，該內存空間的大小等於圖像使用RGB通道所佔用的字節數。
  void *bitmapData; 

  int bitmapByteCount;
  int bitmapBytesPerRow;

  //獲取橫向的像素點的個數
  size_t pixelsWide = CGImageGetWidth(inImage);
  size_t pixelsHigh = CGImageGetHeight(inImage); //縱向

  //每一行的像素點佔用的字節數，每一個像素點的ARGB四個通道各佔8個bit(0-255)的空間
  bitmapBytesPerRow = (int)(pixelsWide * 4); 
  //計算整張圖佔用的字節數
  bitmapByteCount = (int)(bitmapBytesPerRow * pixelsHigh);

  //建立依賴於設備的RGB通道
  colorSpace = CGColorSpaceCreateDeviceRGB();

  //分配足夠容納圖片字節數的內存空間
  bitmapData = malloc(bitmapByteCount); 

  //建立CoreGraphic的圖形上下文，該上下文描述了bitmaData指向的內存空間須要繪製的圖像的一些繪製參數  
  context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast);

  //Core Foundation中經過含有Create、Alloc的方法名字建立的指針，須要使用CFRelease()函數釋放
  CGColorSpaceRelease( colorSpace );

  return context;
}

// 返回一個指針，該指針指向一個數組，數組中的每四個元素都是圖像上的一個像素點的RGBA的數值(0-255)，用無符號的char是由於它正好的取值範圍就是0-255
static unsigned char *RequestImagePixelData(UIImage *inImage)
{
  CGImageRef img = [inImage CGImage];
  CGSize size = [inImage size];

  //使用上面的函數建立上下文
  CGContextRef cgctx = CreateRGBABitmapContext(img); 

  CGRect rect = {{0,0},{size.width, size.height}};

  //將目標圖像繪製到指定的上下文，實際爲上下文內的bitmapData。
  CGContextDrawImage(cgctx, rect, img); 
  unsigned char *data = CGBitmapContextGetData (cgctx);

  //釋放上面的函數建立的上下文
  CGContextRelease(cgctx);
  return data;
}

static void changeRGBA(int *red,int *green,int *blue,int *alpha, const float* f)//修改RGB的值
{
  int redV = *red;
  int greenV = *green;
  int blueV = *blue;
  int alphaV = *alpha;

  *red = f[0] * redV + f[1] * greenV + f[2] * blueV + f[3] * alphaV + f[4];
  *green = f[0+5] * redV + f[1+5] * greenV + f[2+5] * blueV + f[3+5] * alphaV + f[4+5];
  *blue = f[0+5*2] * redV + f[1+5*2] * greenV + f[2+5*2] * blueV + f[3+5*2] * alphaV + f[4+5*2];
  *alpha = f[0+5*3] * redV + f[1+5*3] * greenV + f[2+5*3] * blueV + f[3+5*3] * alphaV + f[4+5*3];

  if (*red > 255)
  {
    *red = 255;
  }
  if(*red < 0)
  {
    *red = 0;
  }
  if (*green > 255)
  {
    *green = 255;
  }
  if (*green < 0)
  {
    *green = 0;
  }
  if (*blue > 255)
  {
    *blue = 255;
  }
  if (*blue < 0)
  {
    *blue = 0;
  }
  if (*alpha > 255)
  {
    *alpha = 255;
  }
  if (*alpha < 0)
  {
    *alpha = 0;
  }
}

+ (UIImage*)imageWithImage:(UIImage*)inImage withColorMatrix:(const float*) f
{
  unsigned char *imgPixel = RequestImagePixelData(inImage);
  CGImageRef inImageRef = [inImage CGImage];
  GLuint w = (GLuint)CGImageGetWidth(inImageRef);
  GLuint h = (GLuint)CGImageGetHeight(inImageRef);

  int wOff = 0;
  int pixOff = 0;

  //雙層循環按照長寬的像素個數迭代每一個像素點
  for(GLuint y = 0;y< h;y++)
  {
    pixOff = wOff;

    for (GLuint x = 0; x

使用方法

UIImage *originImage = [UIImage imageNamed:@testImage]; const float *colorMatrix = colormatrix_lomo; UIImage *filteredImage = [CPUImageFilterUtil imageWithImage:originImage withColorMatrix:colorMatrix];UIImage *originImage = [UIImage imageNamed:@testImage]; const float *colorMatrix = colormatrix_lomo; UIImage *filteredImage = [CPUImageFilterUtil imageWithImage:originImage withColorMatrix:colorMatrix];