How can I add a histogram to a live video preview?
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Paul Jacobs
el 20 de Jul. de 2018
Comentada: Paul Jacobs
el 23 de Jul. de 2018
Hi I'm working on a project where I've created a custom GUI and connected the axes (axes1) to an external camera when a button is pushed and on the same button push a live histogram of the preview image should come up in a different axes. I have gotten the preview to appear and the histogram to appear, however, the histogram does not update itself automatically when the preview image is changed. I've tried everything and need a direction to go on with this. Here's my code below for just the button I'm trying to get working:
function pushbutton1_Callback(hObject, eventdata, handles)
handles = guidata(hObject);
imaqmex('feature', '-previewFullBitDepth', true);
axes(handles.axes1)
vid = videoinput('Camera_source_1', 1, 'MONO16_BIN2x2_1024x1024_SlowMode');
src = getselectedsource(vid);
vidres = vid.VideoResolution;
imWidth = vidres(1);
imHeight = vidres(2);
nBands = vid.NumberOfBands;
himage = image(zeros(imHeight,imWidth, nBands), 'Parent', handles.axes1);
figSize = get(handles.axes1, 'Position');
figWidth = figSize(3);
figHeight = figSize(4);
gca.unit = 'pixels';
gca.position = [((figWidth - imWidth)./2)...
((figHeight - imHeight)./2)...
imWidth imHeight];
vid.FramesPerTrigger = Inf;
src.ExposureTime = user_val(1);
im = preview(vid, himage);
ax = im.Parent;
im.CDataMapping = 'scaled';
colormap(ax, gray);
signalRange = [30 2000];
ax.CLim = signalRange;
axes(handles.axes2)
himage.CData = im.CData;
set(himage, 'CData', im.CData);
imhist(himage.CData, 128)
grid on
grid minor
drawnow
preview(vid, himage)
guidata(hObject, handles);
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Image Analyst
el 21 de Jul. de 2018
I think you're going to have to get a snapshot with getsnapshot() and then histogram that.
3 comentarios
Image Analyst
el 23 de Jul. de 2018
I think you might have to not use preview and just have getsnapshot() and imhist() in a loop. So it's not "live" anymore but a series of snapshots, hopefully the histogramming won't slow it down too much and it will look "live". You might want to do the histogram only every 10 snapshots or so to speed it up.
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