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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Python OpenCV segmentation fault when setting region of interest

I have a python script that contains a class which creates a interactive draggable and movable bounding box. I want to use this to create a region of interest. I am attempting to run this on a video file. To draw the rectangle, the left mouse button…
devman3211
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Creating multiple ROI on webcam video

Im trying to create multiple ROIs over my webcam stream. Ive used this library called roipoly (https://github.com/jdoepfert/roipoly.py) I modified the example code (examples/multi_roi_example.py) to work on webcam , which now looks like this import…
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How to extract an area of a video using coordinates from cv2.rectangle

I'm trying to write a code in Python that should read a video and at any time the user must be able to draw a rectangular area on it. After that I use the rectangle coordinates to extract the area selected from the current frame. This smaller area…
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How do OpenCV's selectROI coordinates work?

I need to use the selectROI function for my project. However, I just can't seem to wrap my head around the format of the coordinates. According to this link, the coordinate array should be in this form: [Top_X, Top_Y, Bottom_X, Bottom_Y]. Assuming…
curd_C
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Reading the values from a seven-segment display

I'm working on a small personal project to automate the data acquisition from different measurement devices (without a digital output); multimeters or luminescence meters. Example of the input image. I've read some tutorials and forum posts on the…
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Why doesn't defroi procedure work on MacOs?

I am working with IDL on MacOS and can't make the defroi procedure work. I can open up the window to define my ROI, but it is unable to mark anything in the image. I tried this exact code on a Windows and it works perfectly fine. What am I doing…
semla
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Do you concentrate more on unit, integration or acceptance tests?

Most gigs I end up at either have little or no unit tests. Typically what are described as the unit tests are actually integration tests and will be rarely run from the developers machine. I usually start my evangelism by preaching the difference…
tddmonkey
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R: how to hand over MIP_GAP option to glpk in ROI

I am using the glpk solver via the roi package in R to solve a mip model. The integer optimization converges very fast to a solution that is within 0.1% of the true optimum but then takes forever if there are a lot of integers to solve for. For…
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Need an explanation how to calculate Return Of Investment for Test Automation

I have this data and i need to calculate RoI for it. But i'm new to this and i don't know how exactly should i do this. Should i calculate it for every day or just total cost of (manual test - automated test) / automated test (something wrong with…
Ars
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Python cv2.error: OpenCV(3.4.1) error: (-215) !_src.empty() in function fastNlMeansDenoising when using calculated values inside array

I am currently using OpenCV and PyTesseract to read image from an ROI specified. Here's what I've come through: import pytesseract import urllib import math import cv2 import numpy as np from unidecode import unidecode from PIL import Image def…
Denny Pradipta
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How to calculate feature map after applying ROI Align, as explained in Mask RCNN Paper?

I was going through slides for mask RCNN given here, but wasn't able to compute the feature map after applying the ROI Align, as given in image below, The paper and slides mention to use Bi-linear Interpolation, but i can't figure how to do that in…
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Why are the sizes of the Mat's different?

I try to crop out a non-rectangular Mat from an image. Followed a lot of tutorials and now I implement this method for my purpose: void crop(Mat src) { Scalar mu, sigma; meanStdDev(src, mu, sigma); Canny(src, dst, mu.val[0] - sigma.val[0],…
Unnamed
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Sort images after ROI (Python, OpenCV)

I am near new to OpenCV world. I am working on a project which need (for now) to detect numbers in an image, select them and save. This is the code I used: # Importing modules import cv2 import numpy as np # Read the input image im =…
BlueTrack
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Detect and Count vehicle and people in opencv python

I am new to OpenCV and have got a project to detect and count the number of vehicles and people in a video taken from a still camera. From Google, I found out that background subtractor helps but have some queries though: What is the use of…
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How to generate a 3d ROI sphere in a specific location within a 3d file (python / nilearn)

My aim is to mask a 3D image at a given location with a 3d spherical mask. I want to extract all of the values of the image within this 3D mask I am currently using python's nilearn.image.NiftiSpheresMasker function to achieve this in the following…
Joe
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