Question

I try to use UIImageView to show the photo. But the Photo sometimes is a little large, and I want to compress it.But I d like to keep its size. For example,a photo is 4M and has a size of 320X480. And I want to compress it and it may have 1M but still has a size of 320X480.

感谢!

Answer 1

利用JPEG压缩压缩压缩电。

lowResImage = [UIImage imageWithData:UIImageJPEGRepresentation(highResImage, quality)];

质量在0.0至1.0之间

http://developer.apple.com/library/ios/#documentation/uikit/参比/UIImage_Class/Reference/Reference.html UIImage documentation, 一切都在上作了解释。

Answer 2

如果你的目标是在具体数据长度以下获取图像,那么就很难猜测你需要什么样的压缩比率,除非你知道来源形象总是一定的数据长度。这里采取简单易变的办法,用jpeg compression实现指标长度......请说1MB,来回答以下问题:

// sourceImage is whatever image you re starting with

NSData *imageData = [[NSData alloc] init];
for (float compression = 1.0; compression >= 0.0; compression -= .1) {
    imageData = UIImageJPEGRepresentation(sourceImage, compression);
    NSInteger imageLength = imageData.length;
    if (imageLength < 1000000) {
        break;
    }
}
UIImage *finalImage = [UIImage imageWithData:imageData];

我看到了一些办法,使用<代码>while,在达到目标规模之前,将图像压缩到9或以任何方式压缩,但我认为,你通过连续压缩/重造图像,正在失去图像质量和过程周期。此外,<<>>>>>代号”此处的路段比较安全,因为它在试图尽量压缩后自动停止。

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