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----------------------------边学边写边学习-------------------------------------

版本：2014a

调用摄像头

a = imaqhwinfo

警告: No Image Acquisition adaptors found. Image acquisition adaptors may be available as downloadable support packages. Open Support Package Installer to install additional vendors.

这时候Support Package Installer在MATLAB里面有下划线，然后你点开它，MATLAB会提供大概13个软件包，这时候选择OS Generic Video Interface下载安装就OK了 (要求注册账号，随便用个邮箱注册下就可以了，不需要付费)。

下面就是调用笔记本电脑摄像头并打开图像

vidDevice = imaq.VideoDevice('winvideo', 1, 'YUY2_640x480', ...

'ROI', [1 1 640 480], ...

'ReturnedColorSpace', 'rgb' );

preview(vidDevice);

人脸检测我们用的是matlab的机器视觉工具箱(瞬间觉得matlab真心强大)

VJ算法的目的是检测人脸，但是其思想同样可以用于检测其他物体，只需进行训练即可。

VJ算法在Matlab里面实现的时候，已经训练好了正脸、侧脸、上半身、眼睛、嘴、鼻子，这些都是可以直接检测，不需训练，直接调用CascadeObjectDetector函数即可。

下面是检测人脸和上半身的例子

% Example 1: Face detection

% ----------------------------

faceDetector = vision.CascadeObjectDetector; % Default: finds faces

I = imread('visionteam.jpg');

bboxes = step(faceDetector, I); % Detect faces

% Annotate detected faces

IFaces = insertObjectAnnotation(I, 'rectangle', bboxes, 'Face');

figure, imshow(IFaces), title('Detected faces');

% Example 2: Upper body detection

% --------------------------------------

bodyDetector = vision.CascadeObjectDetector('UpperBody');

bodyDetector.MinSize = [60 60];

bodyDetector.MergeThreshold = 10;

I2 = imread('visionteam.jpg');

bboxBody = step(bodyDetector, I2); % Detect upper bodies

% Annotate detected upper bodies

IBody = insertObjectAnnotation(I2, 'rectangle', ...

bboxBody, 'Upper Body');

figure, imshow(IBody), title('Detected upper bodies');

至于调用摄像头进行人脸识别，肯定是 调用摄像头的过程中对每一帧图像分别进行识别，然后再在图像中框出来。

这就要求 速度 要足够快。所以检测的时候就要压缩你图像的像素了。

下面放代码

faceDetector = vision.CascadeObjectDetector(); %enable viola jones algorithm

bbox = [100 100 100 100];

vidDevice = imaq.VideoDevice('winvideo', 1, 'YUY2_640x480', ...

'ROI', [1 1 640 480], ...

'ReturnedColorSpace', 'rgb' );

%set(vidDevice.DeviceProperties, 'FrameRate', '30');

boxInserter = vision.ShapeInserter('BorderColor','Custom',...

'CustomBorderColor',[255 255 0]);

textInserter = vision.TextInserter('%d','LocationSource','Input port','Color',[255,255, 0],'FontSize',12);

nFrame =300;

vidInfo = imaqhwinfo(vidDevice);

vidHeight = vidInfo.MaxHeight;

vidWidth = vidInfo.MaxWidth;

videoPlayer = vision.VideoPlayer('Position',[300 100 640+30 480+30]);

for k = 1:nFrame % start recording with 300 frames

tic; % timer start

videoFrame = step(vidDevice); % enable the image capture by webcam

bbox = 4 * faceDetector.step(imresize(videoFrame, 1/4)); % boost video's fps

videoOut = step(boxInserter, videoFrame, bbox); % highlight the boxes of face at video

%release(boxInserter);

step(videoPlayer, videoOut); % display the video live in video player

end

一共执行了300帧，下面放图。

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来源： https://www.cnblogs.com/hyb965149985/p/10193075.html