图片处理--处理成灰色图片

把已知图片处理成灰色的图片。

-(UIImage*)getGrayImage:(UIImage*)sourceImage

{

int width = sourceImage.size.width;

int height = sourceImage.size.height;

CGColorSpaceRef colorSpace =
CGColorSpaceCreateDeviceGray();

CGContextRef context =
CGBitmapContextCreate (nil,width,height,8,0,colorSpace,kCGBitmapByteOrderDefault);

CGColorSpaceRelease(colorSpace);

if (context ==
NULL) {

return
nil;

}

CGContextDrawImage(context,CGRectMake(0,
0, width, height), sourceImage.CGImage);

UIImage *grayImage = [UIImage
imageWithCGImage:CGBitmapContextCreateImage(context)];

CGContextRelease(context);

return grayImage;

}