困惑的UIImageOrientation肖像/风景模式照片 [英] confused by the UIImageOrientation of portrait/landscape mode photo

问题描述

我使用ios的系统相机拍摄了两张照片，其中一张处于纵向模式，另一张处于横向模式，然后我使用imagePicker在我的应用中选择它们：

I take two photos using the ios`s system camera,which one is in portrait mode and another is in landscape mode, then I use imagePicker to pick them out in my app like this:

-(void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

    UIImage* sourceImage = [info objectForKey:UIImagePickerControllerOriginalImage];


    UIImageOrientation imageOrientation = sourceImage.imageOrientation;
    NSLog(@"%d",imageOrientation);

}

注意我NSLog出图像的UIImageOrientation值我刚挑出来。
结果是肖像模式照片的值是3 （代表UIImageOrientationRight）和横向模式照片是0 （UIImageOrientationUp）我只是不明白为什么。有人可以解释一下吗？谢谢！

Note that I NSLog out the UIImageOrientation value of the image I just picked out. the result is the value for the portrait mode photo is 3(which represents UIImageOrientationRight) and the landscape mode photo is 0 (UIImageOrientationUp) I just do not understand why. can anyone explain that? thanks!

推荐答案

iPhone的相机保存照片，无论设备方向如何，但它会为图像添加元信息，以便正确渲染此图像。 imageOrientation 描述了应该旋转图像以正确渲染的度数。

iPhone's camera save photo regardless to the device orientation but it adds a metainformation to image to allow this image rendered properly. imageOrientation describes the amount of degrees the image should be rotated to be properly rendered.

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