How to get normalized coordinates of an ROI?

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Sonia Lenehan 2019-9-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/479942-how-to-get-normalized-coordinates-of-an-roi

回答： Adam Danz 2019-9-11

I am drawing multiple regions of interest on an image and I need to document the position of each to inform anoother script. At the moment I am using the drawrectangle function but it is giving me the position of the ROI in pixels. How do I convert these pixels to normalized cooridinates? I have tried using property inspector and changing the units in there, but it does not work it seems.

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Answer 1

Adam Danz 2019-9-11

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https://ww2.mathworks.cn/matlabcentral/answers/479942-how-to-get-normalized-coordinates-of-an-roi#answer_391423

在 MATLAB Online 中打开

"How do I convert these pixels to normalized cooridinates? "

You can do the conversion yourself by dividing the ROI pixel dimensions by the pixel dimensions of the image.

Here's a working demo you can adjust to your needs.

% Load a matlab demo photo
img = imread('baby.jpg'); 
ims = imshow(img);
% draw ROI
r1 = drawrectangle('Color',[1 0 0]);
% Get pixel dimensions of image (there's several ways to do this)
imagePixelDim = [ims.XData(2),ims.YData(2)];  % [width, height] in pixels
% Normalize the ROI position by the width and height of the image in pixels
r1Norm = r1.Position ./ [imagePixelDim,imagePixelDim];