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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AttributeError: module 'cv2' has no attribute 'selectROI'

I've got a fresh install of OpenCV 3.2 with contribs, ffmpeg, and numpy. However, when I try to use the function selectROI I get an attribute error and I cannot figure out why!!! I've tried to reinstall opencv and opencv-contrib however it doesn't…
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Select a static ROI on webcam video on python openCV

I need to selec a ROI (region of interest), or work area, on a live video from my webcam and take a snapshot of ONLY this work area or ROI, but I can't found how to do this. In this page…
Augusto Meneses
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Draw an ellipse on a figure and get coordinates_Python

I'm working on Python 2.7. I have to define some Areas of Interest (AoI) on a picture. Basically, I'm trying to do this drawing an ellipse (or more) on a specific part of the picture and to get the coordinates (x; y) of its contour. I want to save…
R0bs
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Using ROI in MATLAB

I have a final project in MATLAB and I need help. I build a GUI and display an image using imshow function, now i want to select area from the image and get the pixls of the Selected area. i know the ROI method but i don't know how to use it, so i…
Ofir A.
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Configure properties of boundingRect() in OpenCV (Python)

I have the following code which, given an image, it extract ROI from it. Warning: as is, the code will save all extracted ROIs (45 files) on Desktop. import cv2 extr_path = ('C:\\Users\\Bob\\Desktop\\') # Read the input image im =…
lucians
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How to apply image processing algorithms on the ROI labeled based on a binary mask in Matlab?

I have a binary mask which labeled the foreground of image. Many image processing algorithms such as histogram equalization or otsu method deal with the whole image. My question is how to apply those image processing algorithms so that they can ONLY…
SimaGuanxing
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How to convert the selected rectangle from the image into grayscale?

I need a suggestion how to convert the image in rectangle into a grayscale image. I want to convert the rectangle around the tube to grayscale: for (int i = 612; i >= 0; i = i-204) { cout << "i" << i << endl; rectangle( OI, Rect(i, 0, 161,…
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What's the ROI of using a build tool like ant or nant?

To me this sounds like a really stupid question. Why would you not use a build tool? However, I need to explain my co-worker why he should be using a build tool of some sort. He's getting really into the idea of working as a team with more…
leeand00
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Roi extraction with cv::rect in opencv

I am trying to extract the first quarter of a 100x100 pixel image. I was thinking of using the cv::rect function from a roi-definition (see code example below). Furthermore my original image is part of a vector-array (here in the code-example below,…
iKK
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Draw multiple regions on an image- imfreehand

I'd like to manually draw multiple regions on an image to create a binary mask of the drawn regions (ground truth). I attached the code to do it using imfreehand that does the job for one region, but once in release the mouse button, binary mask for…
user3602648
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latent fingerprint segmentation (finding roi)

I'm trying to make an algorithm that finds the roi of a latent fingerprint. There is no need for minutiae extraction or image enhancement (though some may be necessary), it only needs to find the region of the image that contains the actual…
larstoc
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Error setting ROI OpenCV Android

I am trying to figure out how to set the ROI for an Image in OpenCV on Android. I have done this on other operating systems, so I think HOW I am doing it is semantically correct, but there is an error somewhere. So far I have tried this Rect roi =…
Jameo
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opencv/python: Draw image over a webcam stream

Hey everyone I'm trying to make a game using my webcam where I need some objects to fall down the screen while Im streaming video with my webcam (that stream being my background). The question is: how do I draw the image over this background? I…
Cap.Alvez
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Image copied in ROI doesn't follow camera c++. How to fix this?

I work on Windows7 x64 with opencv and Visual Studio 2010 on c++ language. I created a project in which I show to my camera a rectangular area (call squared_surface). This area is recognized by tracing a rectangle with findSquare () and drawSquares…
Cristina1986
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How to crop the roi of the image

in my project I want to crop the ROI of an image. For this I create a map with the regions of interesst. Now I want to crop the area which has the most important pixels (black is not important, white is important). Has someone an idea how to realize…
501 - not implemented
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