获取图片的每一个像素颜色值

+ (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)x andY:(int)y count:(int)count { NSMutableArray *result = [NSMutableArray arrayWithCapacity:count]; // First get the image into your data buffer CGImageRef imageRef = [image CGImage]; NSUInteger width = CGImageGetWidth(imageRef); NSUInteger height = CGImageGetHeight(imageRef); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); unsigned char *rawData = (unsigned char*) calloc(height * width * 4, sizeof(unsigned char)); NSUInteger bytesPerPixel = 4; NSUInteger bytesPerRow = bytesPerPixel * width; NSUInteger bitsPerComponent = 8; CGContextRef context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGColorSpaceRelease(colorSpace); CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); CGContextRelease(context); // Now your rawData contains the image data in the RGBA8888 pixel format. NSUInteger byteIndex = (bytesPerRow * y) + x * bytesPerPixel; for (int i = 0 ; i < count ; ++i) { CGFloat alpha = ((CGFloat) rawData[byteIndex + 3] ) / 255.0f; CGFloat red = ((CGFloat) rawData[byteIndex] ) / alpha; CGFloat green = ((CGFloat) rawData[byteIndex + 1] ) / alpha; CGFloat blue = ((CGFloat) rawData[byteIndex + 2] ) / alpha; byteIndex += bytesPerPixel; UIColor *acolor = [UIColor colorWithRed:red green:green blue:blue alpha:alpha]; [result addObject:acolor]; } free(rawData); return result; }