图像在 PictureBox 中旋转

Question

正如问题所暗示的，当我将图像加载到 pictureBox 中（使用对话框）时，它不会显示为原始外观。在这个屏幕截图中，左边的图像是我加载到 pictureBox（右边）中的图像。

试图知道是什么原因造成的，我使用画图应用程序绘制图像并使用 Windows 照片查看器旋转它，旋转后的图像按原样加载（旋转），就是这样，有些图片很好装了，其他的都轮换了！我不知道为什么？！

Answer 1

没有原始图像数据，无法确定发生了什么。但很明显，在某些时候，一些涉及图像处理的软件使用了 EXIF 方向属性来旋转图像，而不是实际修改图像数据本身。这可能是照片查看器或在某些时候处理过照片的其他工具。

以下代码可用于检测图像的方向，正如拍摄照片的相机记录在 EXIF 数据中的那样：

static ImageOrientation GetOrientation(this Image image)
{
    PropertyItem pi = SafeGetPropertyItem(image, 0x112);

    if (pi == null || pi.Type != 3)
    {
        return ImageOrientation.Original;
    }

    return (ImageOrientation)BitConverter.ToInt16(pi.Value, 0);
}

// A file without the desired EXIF property record will throw ArgumentException.
static PropertyItem SafeGetPropertyItem(Image image, int propid)
{
    try
    {
        return image.GetPropertyItem(propid);
    }
    catch (ArgumentException)
    {
        return null;
    }
}

其中：

/// <summary>
/// Possible EXIF orientation values describing clockwise
/// rotation of the captured image due to camera orientation.
/// </summary>
/// <remarks>Reverse/undo these transformations to display an image correctly</remarks>
public enum ImageOrientation
{
    /// <summary>
    /// Image is correctly oriented
    /// </summary>
    Original = 1,
    /// <summary>
    /// Image has been mirrored horizontally
    /// </summary>
    MirrorOriginal = 2,
    /// <summary>
    /// Image has been rotated 180 degrees
    /// </summary>
    Half = 3,
    /// <summary>
    /// Image has been mirrored horizontally and rotated 180 degrees
    /// </summary>
    MirrorHalf = 4,
    /// <summary>
    /// Image has been mirrored horizontally and rotated 270 degrees clockwise
    /// </summary>
    MirrorThreeQuarter = 5,
    /// <summary>
    /// Image has been rotated 270 degrees clockwise
    /// </summary>
    ThreeQuarter = 6,
    /// <summary>
    /// Image has been mirrored horizontally and rotated 90 degrees clockwise.
    /// </summary>
    MirrorOneQuarter = 7,
    /// <summary>
    /// Image has been rotated 90 degrees clockwise.
    /// </summary>
    OneQuarter = 8
}

上面的GetOrientation()方法写成一个扩展方法，当然你也可以把它当成一个普通的静态方法来调用。无论哪种方式，只需将您刚刚从文件中打开的 Bitmap 对象传递给它，它就会 return 存储在文件中的 EXIF 方向（如果有的话）。

有了它，您可以根据需要旋转图像。

Answer 2

当您在 Windows 照片查看器中查看图像时，如果 Exif orientation data. PictureBox 没有内置支持此类功能，它会自动更正图像方向。您可以创建一个自定义 PictureBox，即使它们有方向数据也能正确显示图像：

using System.Linq;
using System.Windows.Forms;
using System.Drawing;
using System.ComponentModel;

public class MyPictureBox : PictureBox
{
    private void CorrectExifOrientation(Image image)
    {
        if (image == null) return;
        int orientationId = 0x0112;
        if (image.PropertyIdList.Contains(orientationId))
        {
            var orientation = (int)image.GetPropertyItem(orientationId).Value[0];
            var rotateFlip = RotateFlipType.RotateNoneFlipNone;
            switch (orientation)
            {
                case 1: rotateFlip = RotateFlipType.RotateNoneFlipNone; break;
                case 2: rotateFlip = RotateFlipType.RotateNoneFlipX; break;
                case 3: rotateFlip = RotateFlipType.Rotate180FlipNone; break;
                case 4: rotateFlip = RotateFlipType.Rotate180FlipX; break;
                case 5: rotateFlip = RotateFlipType.Rotate90FlipX; break;
                case 6: rotateFlip = RotateFlipType.Rotate90FlipNone; break;
                case 7: rotateFlip = RotateFlipType.Rotate270FlipX; break;
                case 8: rotateFlip = RotateFlipType.Rotate270FlipNone; break;
                default: rotateFlip = RotateFlipType.RotateNoneFlipNone; break;
            }
            if (rotateFlip != RotateFlipType.RotateNoneFlipNone)
            {
                image.RotateFlip(rotateFlip);
                image.RemovePropertyItem(orientationId);
            }
        }
    }
    [Localizable(true)]
    [Bindable(true)]
    public new Image Image
    {
        get { return base.Image; }
        set { base.Image = value; CorrectExifOrientation(value); }
    }
}

Answer 3

我将我的图像从文件资源管理器加载到 pictureBox，如下所示：

private void btnBrowse_Click ( object sender, EventArgs e ) {
    using( OpenFileDialog openFile = new OpenFileDialog() ) {
        openFile.Title = "Select image for [user]";
        openFile.Filter = "Image files (*.jpg, *.jpeg, *.jpe, *.jfif, *.png)|*.jpg; *.jpeg; *.jpe; *.jfif; *.png|All files (*.*)|*.*";

        if( openFile.ShowDialog() == DialogResult.OK ) {
            //image validation
            try {
                Bitmap bmp = new Bitmap( openFile.FileName );//to validate the image
                if( bmp != null ) {//if image is valid
                    pictureBox1.Load( openFile.FileName );//display selected image file
                    pictureBox1.Image.RotateFlip( Rotate( bmp ) );//display image in proper orientation
                    bmp.Dispose();
                }
            } catch( ArgumentException ) {
                MessageBox.Show( "The specified image file is invalid." );
            } catch( FileNotFoundException ) {
                MessageBox.Show( "The path to image is invalid." );
            }
        }
    }
}

这是正确显示图像方向的方法：

//Change Image to Correct Orientation When displaying to PictureBox
public static RotateFlipType Rotate ( Image bmp ) {
    const int OrientationId = 0x0112;
    PropertyItem pi = bmp.PropertyItems.Select( x => x )
                                .FirstOrDefault( x => x.Id == OrientationId );
    if( pi == null )
        return RotateFlipType.RotateNoneFlipNone;

    byte o = pi.Value[ 0 ];

    //Orientations
    if( o == 2 ) //TopRight
        return RotateFlipType.RotateNoneFlipX;
    if( o == 3 ) //BottomRight
        return RotateFlipType.RotateNoneFlipXY;
    if( o == 4 ) //BottomLeft
        return RotateFlipType.RotateNoneFlipY;
    if( o == 5 ) //LeftTop
        return RotateFlipType.Rotate90FlipX;
    if( o == 6 ) //RightTop
        return RotateFlipType.Rotate90FlipNone;
    if( o == 7 ) //RightBottom
        return RotateFlipType.Rotate90FlipY;
    if( o == 8 ) //LeftBottom
        return RotateFlipType.Rotate90FlipXY;

    return RotateFlipType.RotateNoneFlipNone; //TopLeft (what the image looks by default) [or] Unknown
}

这些是我的参考资料：

代码参考（我修改了接受的答案）：

Visual参考（在评论中找到[我不知道如何link在这里评论]）：http://csharphelper.com/blog/2016/07/read-an-image-files-exif-orientation-data-in-c/

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