1

所以我正在做的是反复压缩图像，直到它适合大小框架。它需要多次尝试，放弃，然后我们告诉用户图像太大了。

我的问题是，在图像大小减小后，当它更改为 UIImage 时，它​​的大小又会变回原样。

这是减小图像大小的代码：

    double compressionRatio = 1;
    int resizeAttempts = 5;

    NSData * imgData = UIImageJPEGRepresentation([info objectForKey:@"UIImagePickerControllerOriginalImage"],compressionRatio);

    NSLog(@"Starting Size: %i", [imgData length]);

    //Trying to push it below around about 0.4 meg
    while ([imgData length] > 400000 && resizeAttempts > 0) {
        resizeAttempts -= 1;

        NSLog(@"Image was bigger than 400000 Bytes. Resizing.");
        NSLog(@"%i Attempts Remaining",resizeAttempts);

        //Increase the compression amount
        compressionRatio = compressionRatio*0.5;

        //Test size before compression
        NSLog(@"Current Size: %i",[imgData length]);
        imgData = UIImageJPEGRepresentation([info objectForKey:@"UIImagePickerControllerOriginalImage"],compressionRatio);

        //Test size after compression
        NSLog(@"New Size: %i",[imgData length]);
    }

    //Set image by comprssed version
    savedImage = [UIImage imageWithData:imgData];

    //Check how big the image is now its been compressed and put into the UIImageView
    NSData *endData = UIImageJPEGRepresentation(savedImage,1.0);
    NSLog(@"Ending Size: %i", [endData length]);

好的，现在这是控制台报告：

Starting Image Size: 4076994

Image was bigger than 400000 Bytes. Resizing.
4 Attempts Remaining
Current Size: 4076994
New Compressed Size: 844482

Image was bigger than 400000 Bytes. Resizing.
3 Attempts Remaining
Current Size: 844482
New Compressed Size: 357459

Ending Image Size: 2090332

如您所见，图像从 4mb 开始。它被压缩到 350kb，最后它被制作成一个 UIImage 为 2mb。

提前感谢任何可以理解这一点的人。

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1 回答 1

1

我稍微修改了你的函数并得到了结果，试试吧，它将我的 10MB 图像减少到 3MB。

-(void)compraseImage
{
    UIImage *largeImage = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

    double compressionRatio = 1;
    int resizeAttempts = 5;

    NSData * imgData = UIImageJPEGRepresentation(largeImage,compressionRatio);

    NSLog(@"Starting Size: %i", [imgData length]);

    //Trying to push it below around about 0.4 meg
    while ([imgData length] > 400000 && resizeAttempts > 0) {
        resizeAttempts -= 1;

        NSLog(@"Image was bigger than 400000 Bytes. Resizing.");
        NSLog(@"%i Attempts Remaining",resizeAttempts);

        //Increase the compression amount
        compressionRatio = compressionRatio*0.5;
        NSLog(@"compressionRatio %f",compressionRatio);
        //Test size before compression
        NSLog(@"Current Size: %i",[imgData length]);
        imgData = UIImageJPEGRepresentation(largeImage,compressionRatio);

        //Test size after compression
        NSLog(@"New Size: %i",[imgData length]);
    }

    //Set image by comprssed version
    savedImage = [UIImage imageWithData:imgData];

    //Check how big the image is now its been compressed and put into the UIImageView

    // *** I made Change here, you were again storing it with Highest Resolution ***
    NSData *endData = UIImageJPEGRepresentation(largeImage,compressionRatio);
    NSLog(@"Ending Size: %i", [endData length]);

    NSString *path = [self createPath:@"myImage.jpg"];
    NSLog(@"%@",path);
    [endData writeToFile:path atomically:YES];
}

-(NSString *) createPath:(NSString *)withFileName
{
    NSArray *paths =NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,
                                                        YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:withFileName];
    return path;
}
于 2013-05-13T09:25:27.113 回答