matlab - 检测视频文件中的人脸。使用数据类型时出错

Question

我有以下问题。我正在使用 matlab 2016。我想使用 Viola-Jones 算法检测视频文件中的人脸。当我尝试在step语句中输入视频文件时，出现以下错误：

Error using
   vision.CascadeObjectDetector/validateInputsImpl
   (line 330)
   Expected input number 2 to be
   one of these types:

   uint8, uint16, double, single,int16

   Instead its type was
   vision.VideoFileReader.

   Error in VJ1_video (line 12)
   bboxes = step(faceDetector, videoFReader);

我知道 VideoFileReader 的类型应该以某种方式转换为以下类型之一：uint8、uint16、double、single、int16。但我不明白如何做到这一点。请告诉我。这是我的程序代码：

clear all;
%Load the video using a video reader object
  videoFReader = vision.VideoFileReader('D:\465.avi');
%Create a detector object.
  faceDetector = vision.CascadeObjectDetector;
%Detect faces.
  bboxes = step(faceDetector, videoFReader);
%Annotate detected faces
  IFaces = insertObjectAnnotation(videoFReader, 'rectangle', bboxes, 'Лицо');
%Create a video player object to play the video file.
  videoPlayer = vision.VideoPlayer;

%Use a while loop to read and play the video frames.
  while ~isDone(videoFReader)
    videoFrame = videoFReader();
    videoPlayer(videoFrame);
  end
%Release the objects.
  release(videoPlayer);
  release(videoFReader);

Answer 1

CascadeObjectDetector 适用于单个帧（图像），而不是帧序列（视频）。因此step，正如您已经建议的那样，函数的输入是图像。更改您的代码，以便在您遍历帧时进行人脸检测。

一个（未经测试的）建议：

    %Load the video using a video reader object
      videoFReader = vision.VideoFileReader('D:\465.avi');
    %Create a video player object to play the video file.
      videoPlayer = vision.VideoPlayer;
    %Create a detector object.
      faceDetector = vision.CascadeObjectDetector;

    %Use a while loop to read and play the video frames.
      while ~isDone(videoFReader)
        videoFrame = videoFReader();
        %Detect faces.
        bboxes = step(faceDetector, videoFReader);
        %Annotate detected faces
        IFaces = insertObjectAnnotation(videoFReader, 'rectangle', bboxes, 'Лицо');
        %Show annotated frames IFaces (instead of videoFrame)
        videoPlayer(IFaces);
      end

    %Release the objects.
      release(videoPlayer);
      release(videoFReader);