錯誤在轉換圖像色彩爲灰度在IOS

在我的應用程序，我有一個ImageView的，然後文我按下一個按鈕時，圖像應改爲黑白錯誤在轉換圖像色彩爲灰度在IOS

我已經使用這個方法

- (UIImage *) convertToGreyscale:(UIImage *)i { 

int kRed = 1; 
int kGreen = 2; 
int kBlue = 4; 

int colors = kGreen; 
int m_width = i.size.width; 
int m_height = i.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), [i 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 sum=0,count=0; 
     if (colors & kRed) {sum += (rgbPixel>>24)&255; count++;} 
     if (colors & kGreen) {sum += (rgbPixel>>16)&255; count++;} 
     if (colors & kBlue) {sum += (rgbPixel>>8)&255; count++;} 
     m_imageData[y*m_width+x]=sum/count; 
    } 
} 
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; 
} 

// 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); 
UIImage *resultUIImage = [UIImage imageWithCGImage:image]; 
CGImageRelease(image); 

free(m_imageData); 

// make sure the data will be released by giving it to an autoreleased NSData 
[NSData dataWithBytesNoCopy:result length:m_width * m_height]; 

return resultUIImage; 
}

，並呼籲它在礦井按鈕移到點擊方法

[self convertToGreyscale:cameraPageView.imageView.image];

但是沒有什麼變化，在圖像中，請誰能幫助我往哪裏去錯

來源

2014-02-10 Chandru

你真的使用CGColorSpaceCreateDeviceRGB來創建灰度圖像嗎？爲什麼不使用CGColorSpaceCreateDeviceGray？也有你看到這個：http://stackoverflow.com/questions/1298867/convert-image-to-grayscale？ – Volker

除了算法中的一些錯誤（灰度不是r，g，b的平均值）之外，麻煩問題是圖像是不可變的。你沒有修改圖片（自我），你正在創建一個新的。

來源

2014-02-10 08:34:41 Sulthan

我不能得到你，請你簡單介紹一下 – Chandru

錯誤在轉換圖像色彩爲灰度在IOS

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