将边界框映射到 Matlab 中的原始图像

Question

我有一个实时皮肤检测算法，它给我一个围绕皮肤区域的边界框，矩形('Position',bb,'EdgeColor','r','LineWidth',2) 来自原始图像。在我使用 Viola Jones 从裁剪的皮肤区域检测面部区域之前，我希望使用代码首先从原始图像检测皮肤区域。我想知道裁剪皮肤区域然后使用人脸检测算法检测人脸后，如何将人脸的边界框映射到原始图像。

function cameraon_Callback(hObject, eventdata, handles)
% hObject    handle to cameraon (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global video;
global videoFrame;
axes(handles.axes1);
video = videoinput('winvideo',1,'YUY2_320x240');
set(video,'ReturnedColorSpace','rgb');
handles.video=video;
triggerconfig(video,'manual');
video.FramesPerTrigger = 1;
guidata(hObject,handles);
faceDetector=vision.CascadeObjectDetector('FrontalFaceCART');
faceDetector.MinSize=[20 20];
faceDetector.MergeThreshold = 20;
videoFrame=getsnapshot(video);
bbox=step(faceDetector,videoFrame);
 if numel(bbox) == 0
    errordlg('Face not detected. Please try again.');
    set(handles.cameraon,'String','Start Camera')
    stop(video);
    delete(video);
    clear;
else
     axes(handles.axes1);
     start(video);
end
while(true)
    frame=getsnapshot(video);
%Detect faces.
data = frame;% this is to read a image from data base. just put any image name u want to give make sure its placed in bin
diff_im = imsubtract(data(:,:,1), rgb2gray(data)); % deleting gray scale pixels from image
diff_im = medfilt2(diff_im, [3 3]); %applying filter one 
diff_im = imadjust(diff_im); % adjust image function to fill small holes (check all the function's functionality to have idea of whats going on)
level = graythresh(diff_im);% extract level value
bw = im2bw(diff_im,level);
BW5 = imfill(bw,'holes');
bw6 = bwlabel(BW5, 8);
stats = regionprops(bw6,['basic']);%basic mohem nist
measurements = regionprops(bw6, 'boundingbox');
BB1=struct2cell(measurements);
BB2=cell2mat(BB1);
a = BB2(1);
b = BB2(2);
c = BB2(3);
d = BB2(4);
[N,M]=size(stats);
if (bw==0)% check if there is no skin color then exit
        break;
else
     tmp = stats(1);
for i = 2 : N % checking for biggest hole to mark it as face 
      if stats(i).Area > tmp.Area
        tmp = stats(i);
      end
 end
bb = tmp.BoundingBox; % applying identification square to mark skin color region
bc = tmp.Centroid;
   videoFrame=getsnapshot(video);

这是我无法将边界框放回原始图像的地方。

   skinImage    = imcrop(videoFrame,bb(1,:));
    bbox = step(faceDetector,skinImage);
  bbox(1,1:2) = bbox(1,1:2) + bb(1,1:2);
      videoOut = insertObjectAnnotation(videoFrame,'rectangle',bbox,'Face'); 
    cla;
    imshow(videoOut,[]);
    drawnow;
    pause(0.0001);
  end
  end
  guidata(hObject,handles);

我想把我从人脸检测器得到的矩形放在全尺寸图像上，在图像中裁剪图像的原始位置。

Answer 1

您只需将裁剪区域的左上角坐标添加到检测到的边界框的左上角即可。

另外，在最新版本的MATLAB中vision.CascadeObjectDetector支持传入要检测物体的感兴趣区域，这样就不需要裁剪了。然后它会为你调整坐标。查看 vision.CascadeObjectDetector 的 step() 方法的文档。

将边界框映射到 Matlab 中的原始图像

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