Objective Cを使用してRGBカラー画像をグレースケール画像に変更

Question

カラー画像をグレー画像に変更するアプリケーションを開発していました。しかし、どのように画像が間違って出てくる。私はコードに何が間違っているのか分かりません。多分私が入れたパラメータが間違っていると助けてください。

UIImage *c = [UIImage imageNamed:@"downRed.png"]; 
CGImageRef cRef = CGImageRetain(c.CGImage); 

NSData* pixelData = (NSData*) CGDataProviderCopyData(CGImageGetDataProvider(cRef)); 

size_t w = CGImageGetWidth(cRef); 
size_t h = CGImageGetHeight(cRef); 

unsigned char* pixelBytes = (unsigned char *)[pixelData bytes]; 

unsigned char* greyPixelData = (unsigned char*) malloc(w*h); 

for (int y = 0; y < h; y++) { 
for(int x = 0; x < w; x++){ 

int iter = 4*(w*y+x); 
int red = pixe lBytes[iter]; 
int green = pixelBytes[iter+1]; 
int blue = pixelBytes[iter+2]; 
greyPixelData[w*y+x] = (unsigned char)(red*0.3 + green*0.59+ blue*0.11); 
    int value = greyPixelData[w*y+x]; 

} 
} 

CFDataRef imgData = CFDataCreate(NULL, greyPixelData, w*h); 


CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData(imgData); 


size_t width = CGImageGetWidth(cRef); 
size_t height = CGImageGetHeight(cRef); 
size_t bitsPerComponent = 8; 
size_t bitsPerPixel = 8; 
size_t bytesPerRow = CGImageGetWidth(cRef); 
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); 
CGBitmapInfo info = kCGImageAlphaNone; 
CGFloat *decode = NULL; 
BOOL shouldInteroplate = NO; 
CGColorRenderingIntent intent = kCGRenderingIntentDefault; 
    CGDataProviderRelease(imgDataProvider); 

CGImageRef throughCGImage = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpace, info, imgDataProvider, decode, shouldInteroplate, intent); 


UIImage* newImage = [UIImage imageWithCGImage:throughCGImage]; 

CGImageRelease(throughCGImage); 
newImageView.image = newImage; 

Answer 1

ただ、この使用：誰かがdigipeopleが提供するソリューションは、その周りに黒いマスクを持つことになります透明部分が含まれているスケール画像をグレーしたい場合

- (UIImage *)convertImageToGrayScale:(UIImage *)image 
{ 
    // Create image rectangle with current image width/height 
    CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height); 

    // Grayscale color space 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); 

    // Create bitmap content with current image size and grayscale colorspace 
    CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone); 

    // Draw image into current context, with specified rectangle 
    // using previously defined context (with grayscale colorspace) 
    CGContextDrawImage(context, imageRect, [image CGImage]); 

    // Create bitmap image info from pixel data in current context 
    CGImageRef imageRef = CGBitmapContextCreateImage(context); 

    // Create a new UIImage object 
    UIImage *newImage = [UIImage imageWithCGImage:imageRef]; 

    // Release colorspace, context and bitmap information 
    CGColorSpaceRelease(colorSpace); 
    CGContextRelease(context); 
    CFRelease(imageRef); 

    // Return the new grayscale image 
    return newImage; 
} 

Answer 2

を。これをそのまま使用して、そのまま透明にしておきます。

- (UIImage *)imageToGreyImage:(UIImage *)image { 
    // Create image rectangle with current image width/height 
    CGFloat actualWidth = image.size.width; 
    CGFloat actualHeight = image.size.height; 

    CGRect imageRect = CGRectMake(0, 0, actualWidth, actualHeight); 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); 

    CGContextRef context = CGBitmapContextCreate(nil, actualWidth, actualHeight, 8, 0, colorSpace, kCGImageAlphaNone); 
    CGContextDrawImage(context, imageRect, [image CGImage]); 

    CGImageRef grayImage = CGBitmapContextCreateImage(context); 
    CGColorSpaceRelease(colorSpace); 
    CGContextRelease(context); 

    context = CGBitmapContextCreate(nil, actualWidth, actualHeight, 8, 0, nil, kCGImageAlphaOnly); 
    CGContextDrawImage(context, imageRect, [image CGImage]); 
    CGImageRef mask = CGBitmapContextCreateImage(context); 
    CGContextRelease(context); 

    UIImage *grayScaleImage = [UIImage imageWithCGImage:CGImageCreateWithMask(grayImage, mask) scale:image.scale orientation:image.imageOrientation]; 
    CGImageRelease(grayImage); 
    CGImageRelease(mask); 

    // Return the new grayscale image 
    return grayScaleImage; 
} 

Answer 3

スウィフトバージョン、テストされ、100％の作業：

func imageToGreyImage(image: UIImage) -> UIImage { 

    // Create image rectangle with current image width/height 
    var actualWidth = image.size.width; 
    var actualHeight = image.size.height; 

    var imageRect = CGRectMake(0, 0, actualWidth, actualHeight); 
    var colorSpace = CGColorSpaceCreateDeviceGray(); 

    var bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.None.rawValue) 

    var context = CGBitmapContextCreate(nil, Int(actualWidth), Int(actualHeight), 8, 0, colorSpace, bitmapInfo); 
    CGContextDrawImage(context, imageRect, image.CGImage); 

    var grayImage = CGBitmapContextCreateImage(context); 
    bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.Only.rawValue) 
    context = CGBitmapContextCreate(nil, Int(actualWidth), Int(actualHeight), 8, 0, nil, bitmapInfo); 
    CGContextDrawImage(context, imageRect, image.CGImage); 
    var mask = CGBitmapContextCreateImage(context); 

    var grayScaleImage = UIImage(CGImage: CGImageCreateWithMask(grayImage, mask), scale: image.scale, orientation: image.imageOrientation) 

    // Return the new grayscale image 
    return grayScaleImage!; 
} 

、Uは何のアルファが欲しいない場合は、単に次の行を削除：

bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.Only.rawValue)