将图像转换成偏光过滤

Question

我试图将图像转换成偏光过滤器通过以下方式：

int m_width = self.size.width; 
    int m_height = self.size.height; 

    uint32_t *rgbImage = (uint32_t *) malloc(m_width * m_height * sizeof(uint32_t)); 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    CGContextRef context = CGBitmapContextCreate(
               rgbImage, 
               m_width, 
               m_height, 
               8, 
               m_width * 4, 
               colorSpace, 
               kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast 
               ); 
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh); 
    CGContextSetShouldAntialias(context, NO); 
    CGContextDrawImage(context, CGRectMake(0, 0, m_width, m_height), [self CGImage]); 
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 

    // now convert to grayscale 
    uint8_t *m_imageData = (uint8_t *) malloc(m_width * m_height); 
    for(int y = 0; y < m_height; y++) 
    { 
     for(int x = 0; x < m_width; x++) 
     { 
      uint32_t rgbPixel=rgbImage[y*m_width+x]; 
      uint32_t redIn = 0, greenIn = 0,blueIn = 0,max = 0,min = 0,chroma = 0,hue = 0,saturation = 0,redOut = 0,greenOut = 0,blueOut = 0; 

      redIn = (rgbPixel>>24)&255; 
      greenIn = (rgbPixel>>16)&255; 
      blueIn = (rgbPixel>>8)&255; 

      //NSLog(@"redIn %u greenIn %u blueIn %u",redIn,greenIn,blueIn); 

      max = redIn > greenIn ? redIn > blueIn ? redIn : blueIn : greenIn > blueIn ? greenIn : blueIn; 
      min = redIn < greenIn ? redIn < blueIn ? redIn : blueIn : greenIn < blueIn ? greenIn : blueIn; 
      chroma = max - min; 

      if(chroma != 0) 
      { 
       if(max == redIn) 
        hue = ((greenIn - blueIn)/chroma) %6 ; 
       else if(max == greenIn) 
        hue = ((blueIn - redIn)/chroma) + 2; 
       else if(max == blueIn) 
        hue = ((redIn - greenIn)/chroma) + 4; 

       hue = (hue+20)%6; 

       if(chroma != 0) 
        saturation = chroma/max; 

       if(hue >= 0 && hue < 1) 
       { 
        redOut = chroma + max - chroma; 
        greenOut = chroma * (1 - abs((hue % 2) - 1)) + max - chroma; 
        blueOut = 0 + max - chroma; 
       } 
       else if(hue >= 1 && hue < 2) 
       { 
        redOut = chroma * (1 - abs((hue % 2) - 1)) + max - chroma; 
        greenOut = chroma + max - chroma; 
        blueOut = 0 + max - chroma; 
       } 
       else if(hue >= 2 && hue < 3) 
       { 
        redOut = 0 + max - chroma; 
        greenOut = chroma + max - chroma; 
        blueOut = chroma * (1 - abs((hue % 2) - 1)) + max - chroma; 
       } 
       else if(hue >= 3 && hue < 4) 
       { 
        redOut = 0 + max - chroma; 
        greenOut = chroma * (1 - abs((hue % 2) - 1)) + max - chroma; 
        blueOut = chroma + max - chroma; 
       } 
       else if(hue >= 4 && hue < 5) 
       { 
        redOut = chroma * (1 - abs((hue % 2) - 1)) + max - chroma; 
        greenOut = 0 + max - chroma; 
        blueOut = chroma + max - chroma; 

       } 
       else if(hue >= 5 && hue < 6) 
       { 
        redOut = chroma + max - chroma; 
        greenOut = 0 + max - chroma; 
        blueOut = chroma * (1 - abs((hue % 2) - 1)) + max - chroma; 
       } 
      } 
      //NSLog(@"redOut %u greenOut %u blueOut %u",redOut,greenOut,blueOut); 
      m_imageData[y*m_width+x]=redOut + greenOut + blueOut; 
     } 
    } 
    free(rgbImage); 

    // convert from a gray scale image back into a UIImage 
    uint8_t *result = (uint8_t *) calloc(m_width * m_height *sizeof(uint32_t), 1); 

    // process the image back to rgb 
    for(int i = 0; i < m_height * m_width; i++) 
    { 
     result[i*4]=0; 
     int val=m_imageData[i]; 
     result[i*4+1]=val; 
     result[i*4+2]=val; 
     result[i*4+3]=val; 
    } 
    free(m_imageData); 

    // create a UIImage 
    colorSpace = CGColorSpaceCreateDeviceRGB(); 
    context = CGBitmapContextCreate(result, 
            m_width, 
            m_height, 
            8, 
            m_width * sizeof(uint32_t), 
            colorSpace, 
            kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast 
            ); 
    CGImageRef image = CGBitmapContextCreateImage(context); 
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 
#ifdef kNYXReturnRetainedObjects 
    UIImage* resultUIImage = [[UIImage alloc] initWithCGImage:image]; 
#else 
    UIImage *resultUIImage = [UIImage imageWithCGImage:image]; 
#endif 
    CGImageRelease(image); 

    free(result); 

    return resultUIImage; 

但我执行后没获得宝丽来图片的代码。 这段代码有什么问题，或者你可以以其他方式给我建议。

Answer 1

代码最明显的问题是，在该方法结束时，您创建一个绘图上下文，不做任何事情，然后从中获取图像并将其作为UIImage返回。据推测，这将是空白的。我想你想获得在数据result举行的形象 - 我认为你需要在CGImageCreate寻找替代，而不是建立一个新的上下文。

的信息，请参阅here创建原始数据，您将需要传递给CGImageCreate数据提供者。这一切看起来相当复杂。