帮我用matlab写一个使用帧差法检测运动目标并且显示目标轮廓的代码

好的，以下是使用帧差法检测运动目标并显示目标轮廓的Matlab代码：

%% 读取视频文件
videoFile = 'example.mp4';
videoReader = VideoReader(videoFile);

%% 设置变量
% 设定光流法所需的变量
opticFlow = opticalFlowFarneback;
frameLast = rgb2gray(readFrame(videoReader)); % 读取第一帧
% 定义轮廓的颜色为红色
linColor = [1 0 0];

%% 循环读取视频一帧一帧的处理
while hasFrame(videoReader)
frameCurrent = rgb2gray(readFrame(videoReader)); % 读取当前帧

% 计算运动光流并计算光流密度
flow = estimateFlow(opticFlow, frameLast);
flowMag = flow.Magnitude;
flowMagMedian = median(flowMag(:));

% 计算光流梯度
if (flowMagMedian > 0)
gradThresh = 0.1 * flowMagMedian;
else
gradThresh = 0.1;
end
gradSizeFilter = 10;
gMag = imgradient(flow.Magnitude);
gMagThresh = (gMag > gradThresh) & (flow.Magnitude > 0);
gMagThresh = bwareaopen(gMagThresh, gradSizeFilter);

% 生成轮廓
fillImage = uint8(gMagThresh) .* 255;
boundary = bwboundaries(fillImage, 'noholes');
if (~isempty(boundary))
for k = 1:length(boundary)
xBoundary = boundary{k}(:,2);
yBoundary = boundary{k}(:,1);
plot(xBoundary, yBoundary, 'Color', linColor, 'LineWidth', 2);
end
end

% 更新变量
frameLast = frameCurrent;
end

%% 显示结果
title('检测的目标轮廓');