相册选择图片，图片4:3处理

- (UIImage *)handleImage:(UIImage *)originalImage

{

CGSize originalsize = [originalImage size];

CGImageRef imageRef = nil;

CGFloat tempWidth = originalsize.width*0.75;

CGFloat imageW = originalsize.width;

imageRef = CGImageCreateWithImageInRect([originalImage CGImage], CGRectMake(0, originalsize.height/2-tempWidth*0.5, imageW, tempWidth));//获取图片整体部分

UIGraphicsBeginImageContext(CGSizeMake(imageW, tempWidth));//指定要绘画图片的大小

CGContextRef con = UIGraphicsGetCurrentContext();

CGContextTranslateCTM(con, 0.0, tempWidth);

CGContextScaleCTM(con, 1.0, -1.0);

CGContextDrawImage(con, CGRectMake(0, 0, imageW, tempWidth), imageRef);

UIImage *standardImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

CGImageRelease(imageRef);

return standardImage;

}

使用：

UIImage *newImage =  [self handleImage:image];