how to draw a free hand box on an image to select that region of interest?

Question

Manoj Kumar 2014-12-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/167730-how-to-draw-a-free-hand-box-on-an-image-to-select-that-region-of-interest

评论： Sean de Wolski 2015-1-27

采纳的回答： Sean de Wolski

在 MATLAB Online 中打开

hi,

I used this for free hand drawing in an irregular shape. But I need to draw a box to select a region.

 % Get the input free hand image
 figure, imshow(grayImage, []);
 axis on;
 title('Contour Region Required', 'FontSize', fontSize);
 set(gcf, 'Position', get(0,'Screensize')); % Maximize figure.
 message = sprintf('Left click and hold to begin drawing.\nRelease Mouse Button when Completed');
 uiwait(msgbox(message));
 hFH = imfreehand();
 % Create a binary image ("mask") from the ROI object.
 binaryImage = hFH.createMask();
 xy = hFH.getPosition;
 % Label the binary image and compute the centroid and center of mass.
 labeledImage = bwlabel(binaryImage);
 % Will keep only the part of the image that's inside the mask, zero outside mask.
 blackMaskedImage = grayImage;
 blackMaskedImage(~binaryImage) = 0;

Can you please suggest me free hand drawing a box.

Thanks...

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Answer 1

Sean de Wolski 2014-12-22

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To force it to a rectangle, use imrect which has the same api as imfreehand.

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Manoj Kumar 2015-1-27

Is there any way that after drawing the box, Can i rotate it ( I mean can I perform any orientation to the box)?

Sean de Wolski 2015-1-27

Not easily. You would have to build a second impoly and then manually transform its vertices.

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Answer 2

Chad Greene 2014-12-22

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https://ww2.mathworks.cn/matlabcentral/answers/167730-how-to-draw-a-free-hand-box-on-an-image-to-select-that-region-of-interest#answer_163103

If you have the Image Processing Toolbox, http://www.mathworks.com/help/images/ref/imfreehand.html

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Image Analyst 2014-12-22

imfreehand() is for an irregular shape (and he's already using that), not for a perfect box with straight sides.

Chad Greene 2014-12-22

ah, good catch.

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Answer 3

Image Analyst 2014-12-22

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https://ww2.mathworks.cn/matlabcentral/answers/167730-how-to-draw-a-free-hand-box-on-an-image-to-select-that-region-of-interest#answer_163131

在 MATLAB Online 中打开

If you don't have the Image Processing Toolbox, you can use rbbox():

k = waitforbuttonpress;
point1 = get(gca,'CurrentPoint');    % button down detected
finalRect = rbbox;                   % return figure units
point2 = get(gca,'CurrentPoint');    % button up detected
point1 = point1(1,1:2);              % extract x and y
point2 = point2(1,1:2);
p1 = min(point1,point2);             % calculate locations
offset = abs(point1-point2);         % and dimensions
% Find the coordinates of the box.
xCoords = [p1(1) p1(1)+offset(1) p1(1)+offset(1) p1(1) p1(1)];
yCoords = [p1(2) p1(2) p1(2)+offset(2) p1(2)+offset(2) p1(2)];
x1 = round(xCoords(1));
x2 = round(xCoords(2));
y1 = round(yCoords(5));
y2 = round(yCoords(3));
hold on
plot(xCoords, yCoords, 'b-'); % redraw in dataspace units

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Manoj Kumar 2014-12-24

Then how to get the coordinates of the two points that I use to make a rectange using imrect()?

Image Analyst 2014-12-24

Did you overlook how I get x1,x2,y1,y2?

And you don't use imrect anymore - this is used in place of it. One advantage is that you just drag out a box and you're done. It doesn't let you adjust the size (of course you could put it in a loop where you redraw it) but you don't have the extra step of having to double-click inside the box (which is confusing to users - they won't know to do that unless you give them instructions in advance).

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