图片缩放

// int h = image.size.height;
// int w = image.size.width;
// // if(h <= 320 && w <= 480)
//// {
////
//// }
//// else
//// {
// //float b = (float)320/w < (float)480/h ? (float)320/w : (float)480/h;
// //float b=0.5f;
// CGSize itemSize = CGSizeMake(w/2, h/2);
// UIGraphicsBeginImageContext(itemSize);
// CGRect imageRect = CGRectMake(0, 0, w/2, h/2);
// [image drawInRect:imageRect];
// image = UIGraphicsGetImageFromCurrentImageContext();
// UIGraphicsEndImageContext();
// //}