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Questions tagged [roi]

Region Of Interest, a region of an image on which algorithms are executed on.

Region Of Interest (ROI) is a selected subset of a data set identified for a particular purpose and is commonly used in many application areas. The data set could be any of the following:

  • 1D data set: a time or frequency interval on a waveform
  • 2D data set: the boundaries of an object on an image
  • 3D data set: the contours or surfaces outlining an object (a.k.a. the Volume of Interest (VOI)) in a volume
  • 4D data set: the outline of an object at or during a particular time interval in a time-volume

Tag Usage:

An ROI on an image can be defined in different formats, like a , a or a set of . The tag is commonly used in question related to or . An ROI can be defined to:

  • Restrict the region of the data set that an algorithm is applied to and avoid unnecessary calculations. (e.g., in an )
  • Identify/Annotate a part of data set. (e.g., locate moving objects in )
  • Extract additional information from the data set. (e.g., measure size of a tumor on a medical image)

An Example:

ROI locates the boundaries of a registration plate (it's Persian), this area will be used for ANPR:

enter image description here

Additional Reading:

Region of Interest on Wikipedia

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Get center pixels of image in matlab

I want to extract a rectangular region of size (p*hight,p*width,3) of an image. p is a double value between [0,1]. The follwoing code works but I would like to know if there is a better way to achieve this? img = imread(ImageName); % size…
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ROI-based KLT optical tracker in opencv

How can I add roi-based selection in lkdemo.pp( klt optical flow tracker opencv example) source code? I want select roi in the first frame and track feature point that selected in roi. #include "opencv2/video/tracking.hpp" #include…
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How to get user freehand input in matlab?

I am trying to write a handwriting recognization software, and need user input. I can successfully use imfreehand (with parameter, closed = 0) function to let the user write on top of a blank plot axis. However, I have two issues with that: I…
rajendra
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MATLAB: How to make 2D binary mask from mesh?

I'm using MESH2D in Matlab in order to mesh ROI (Region Of Interest) from images. Now I would like to make binary masks from these triangular meshes. The outputs from [p,t] = mesh2d(node) are: p = Nx2 array of nodal XY co-ordinates. t = Mx3…
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How to specify ROIs from left to right in MAtlab

I'm a fresher to Matlab. I'm working on vision.CascadeObjectDetector on Mat-lab and is used twice to find-out two different objects(separately trained), say E and K from a video. bbox and bbox2 are respective ROIs. part of code is given below while…
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Saving Images of Detected Faces in OpenCV

I have a code that detects faces and saves multiple cropped area images of them to a file path. My code doesn't stop saving images of detected faces until I physically close the program. For every one second a face is detected on a webcam, my code…
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How to extract a line of pixels (roi) from video, combined lines in a single .tif image?

I am new to programming and I am trying to use ImageJ and Jython to extract a single line from a video and combine the lines into a time progression. I am trying to create a videokymogram (i.e. http://www.kymography.com/supp_demo.html)! My attempt…
Always_learning
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How to find the Non-Square ROI of an image?

I'm looking for a way to find a non-square region of interest. I've seen examples on here where it's all rectangular based. For example here they find the tilted rectangle. I've looked at code examples like this SO page where they draw a…
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Stereo rectify - ROI have different sizes

I have done a stereo calibration and I got the validPixROI1 and 2 (green border). Now I want to use StereoSGBM but the rois from calibration (from stereoRectify) are not the same size. Anyone know how to solve this? Actually I do somethine linke…
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Remove imellipse after double click MATLAB

Just wondering how I can get rid of the imellipse after calling it in MATLAB. Currently I call it, double click it to plot the ellipse on my image, then I want to remove the ellipse tool. I have a GUI, which I click a pushbutton to make an…
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Plot imellipse over image in MATLAB

I am trying to make a binary region of interest mask over an image stack (GUI). Here is what I have thus far: % Initalize lesion mask LesionMask = zeros(size(handles.ImageOne)); % Create an ellipse for roi analysis Lesion =…
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OpenCV and cvAvgSdv with a Mask (roi)

I am trying to average the pixel value of an image across a circular region of interest. I am trying to use cvAvgSdv and it returns a sensible mean, but zero standard deviation. I also try cvCountNonZero which also returns zero. Must be a basic…
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Selecting an ellipse as a region of interest (ROI)

I used imellipse to select an ellipse as my region of interest (ROI). The issue is that the ellipse I want to select is of around 45 degrees, and, when I use imellipse, it seems it is 90 degrees either horizontally or vertically. How can I change…
user3481560
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Feature extraction: Divide the ROI into small windows(patches) or let it be as ROI?

I am interested in feature extraction of the ROI of an image, which will be used as feature vectors input to an SVM. The features to be extracted include the texture(color co-occurence/haralick features) and color(rgb-histogram, 4 bins and mean r,…
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Drawing a region of interest in a scatter plot and printing the points contained in matplotlib

In a scatterplot matrix, I want to draw a region of interest(ROI) and print the points that are contained in that region. For the time being, I can draw regions in the subplots but I do not know how to get and print the points that are contained in…
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