c# - 剪切图像 EmguCV

Question

目前我正在尝试编写一个检测人脸的小程序。

我想将用于检测的灰框切割成检测到的面部矩形大小的 block 。

这是我的操作方法:

public List<PreviewImage> GetDetectedSnippets(Capture capture, ProcessType processType)
{
    var mat = capture?.QueryFrame();

    var imageList = new List<PreviewImage>();
    if (mat == null)
        return imageList;

    var imageframe = mat.ToImage<Bgr, byte>();
    var grayframe = imageframe.Convert<Gray, byte>();

    Rectangle[] faces = null;

    try
    {
        switch (processType)
        {
            case ProcessType.Front:
                {
                    faces = _cascadeFrontDefault.DetectMultiScale(grayframe, 1.25, 10, Size.Empty);

                }
                break;

            case ProcessType.Profile:
                {
                    faces = _cascadeProfileFace.DetectMultiScale(grayframe, 1.25, 10, Size.Empty);
                }
                break;

            default:
                {
                    return imageList;
                }
        }
    }
    catch (Exception ex)
    {
        Debug.WriteLine("Could not process snapshot: " + ex);
        return imageList;
    }


    foreach (var face in faces)
    {
        var detectedImage = imageframe.Clone();
        detectedImage.Draw(face, new Bgr(Color.BlueViolet), 4);


        var detectedGrayframe = grayframe.GrabCut(face, 1); // This isn't working. Here should the grayframe be cutted into a smaller piece.

        imageList.Add(new PreviewImage(detectedImage, detectedGrayframe));
    }

    return imageList;
}

这是 PreviewImage 类:

public class PreviewImage
{
    public Image<Bgr, byte> Original { get; }
    public Image<Gray, byte> Grayframe { get; }

    public PreviewImage(Image<Bgr, byte> original, Image<Gray, byte> grayframe)
    {
        Original = original;
        Grayframe = grayframe;
    }
}

如何将灰框切成给定矩形大小的一 block ？

Answer 1

这将完成工作:

grayframe.ROI = face;
var detectedGrayframe = grayframe.Copy();
grayframe.ROI = Rectange.Empty;