Question

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

我的问题是，在图像尺寸减小后，当它变为UIImage时，它的尺寸会再次恢复。

以下是缩小图像尺寸的代码：

    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]);

好了，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

正如你所看到的那样，图像开始于4mb大。它被压缩到350kb，最后它被制成一个2mb的UIImage。

提前感谢任何能够理解这一点的人。

Answer 1

我已经修改了你的功能并得到了结果，尝试一下，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;
}

压缩大型UIImage

1 个答案: