Plot on top of a Live Image Preview

Question

Allison Liu ，2019-1-23

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https://ww2.mathworks.cn/matlabcentral/answers/441148-plot-on-top-of-a-live-image-preview

评论： Allison Liu ，2019-2-7

Hello,

I am trying to plot a few points on top of a live image preview, but my code returns an error of "Line cannot be a child of Image." Does anyone know of a way to plot on top of a Live Image, similar to the imageMarker function?

vidRes1 = handles.vid1.VideoResolution;
imWidth1 = vidRes1(1);
imHeight1 = vidRes1(2);
nBands1 = handles.vid1.NumberOfBands;
hImage = image(zeros(imHeight1, imWidth1, nBands1), 'Parent', handles.axes1);
preview(handles.vid1, hImage);
plot(hImage, 250, 300, 'bo');

Thanks,

Allison

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Answer 1

Andrei Ursache 2019-2-1

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https://ww2.mathworks.cn/matlabcentral/answers/441148-plot-on-top-of-a-live-image-preview#answer_359112

Allison,

This approach might work for you:

vid = videoinput('winvideo', 1);
vidInfo = imaqhwinfo(vid);
vidRes = vid.VideoResolution;
imWidth = vidRes(1);
imHeight = vidRes(2);
numBands = vid.NumberOfBands;
hFig = figure;
hAxes = axes(hFig);
hImage = image(hAxes, zeros(imHeight, imWidth, numBands, vidInfo.NativeDataType));
preview(vid, hImage);
hLine = line(hAxes, round([0.25*imWidth, 0.75*imWidth]),...
    round([0.5*imHeight, 0.5*imHeight]),...
    'Marker', 'o',...
    'LineStyle', 'none');