小賢的部落格

const NSUInteger bitsPerComponent = 8;

const NSUInteger bytesPerPixel = 4;

/**

 return r,g,b,a

 */

+ (NSData*)getRGBAsFromImage:(UIImage*)image atX:(int)xx andY:(int)yy count:(int)count

{

    // First get the image into your data buffer

    CGImageRef imageRef = [image CGImage];

    NSUInteger width = CGImageGetWidth(imageRef);

    NSUInteger height = CGImageGetHeight(imageRef);

    NSUInteger size = height * width * bytesPerPixel;

    NSUInteger bytesPerRow = bytesPerPixel * width;

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    unsignedchar *rawData = (unsignedchar*) calloc(size, sizeof(unsignedchar));

    CGContextRef context = CGBitmapContextCreate(rawData, width, height,

                                                 bitsPerComponent, bytesPerRow, colorSpace,

                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);

    CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);

    NSData *data = [NSData dataWithBytes:rawData length:count];

    CGContextRelease(context);

    free(rawData);

    CGColorSpaceRelease(colorSpace);

    return data;

}

+ (void)setImageFromData:(NSData*)data width:(NSUInteger)width height:(NSUInteger)height destImage:(UIImage**)destImage

{

    Byte *rawData = (Byte *)data.bytes;

    CFIndex count = data.length;

    NSUInteger bytesPerRow = bytesPerPixel * width;

    CFDataRef rgbData = CFDataCreate(NULL, rawData, count);

    CGDataProviderRef provider = CGDataProviderCreateWithCFData(rgbData);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGImageRef imageRef = CGImageCreate(width,

                                        height,

                                        bitsPerComponent,

                                        bytesPerPixel * 8,

                                        bytesPerRow,

                                        colorSpace,

                                        kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big,

                                        provider,

                                        nil,

                                        NO,

                                        kCGRenderingIntentDefault);

    *destImage = [UIImage imageWithCGImage:imageRef];

    CGImageRelease(imageRef);

    CGColorSpaceRelease(colorSpace);

    CGDataProviderRelease(provider);

    CFRelease(rgbData);

}

參考資料:

http://stackoverflow.com/questions/448125/how-to-get-pixel-data-from-a-uiimage-cocoa-touch-or-cgimage-core-graphics

http://stackoverflow.com/questions/2261177/cgimage-from-byte-array

http://stackoverflow.com/questions/2838038/c-programming-malloc-inside-another-function

https://stackoverflow.com/questions/8915630/ios-uiimageview-how-to-handle-uiimage-image-orientation/15039609#15039609