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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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Using ROI in OpenCV?

ROI can only be implemented with an rectangle. I however have a contour that I want to set as an ROI. Does anyone have an idea of how I would go about using a contour as an ROI rather than a rectangle? Otherwise if not possible, how could I focus my…
user1017485
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CIFilter applying to selected area using swift - ROI

I am using CIFilter for editing video and images with Swift 3.0. Its working fine, for whole image or video.But I want to apply filter to only selected area. I found, It can be done through ROI But, all the documentation i found, is related to…
PlusInfosys
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ValueError: Shape must be rank 1 but is rank 0 for 'ROIAlign/Crop' (op: 'CropAndResize') with input shapes: [2,360,475,3], [1,4], [], [2]

I tried to give all input in this function but it comes out problem like below , i not sure what is the empty [] is . There are 2 image image in RGB and the original code is from…
Go Go Gadget 2
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How can I find contours inside ROI using opencv and Python?

Im trying to find contours in a specific area of the image. Is it possible to just show the contours inside the ROI and not the contours in the rest of the image? I read in another similar post that I should use a mask, but I dont think I used it…
agrom
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openCV AdaptiveThreshold versus Otsu Threshold. ROI

I'm tried to use both of the methods but it seems like Adaptive threshold seems to be giving a better result. I used cvSmooth( temp, dst,CV_GAUSSIAN,9,9, 0); on the original image then only i used the threshold. Is there anything I can tweak…
user3396218
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Matlab: Real-time plotting of ROI selected with IMRECT

I have a GUI with two axes. The first axes has a low-resolution image. What I would like to do is select an area on the first axes using IMRECT and then display that area as a high-resolution image on the second axes, while continuously updating as…
user1668909
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Algorithm for optimal placement of cropped regions to capture features (blobs) in an image

I have a large image which contains "blobs" of interest over a background. I have the position (centroid, bounding box, area) of all blobs. I want to crop a limited number of regions of a fixed size in the image that allow me to capture most of the…
Jean-Olivier Irisson
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How do I measure RGB mean in a unique ROI?

I have two images, an analysis image and an ROI Mask image (the ROI Mask image is below). What I want to do is to measure the RGB mean value in an area of the analysis image selected by the ROI Mask image. I am doing this by using a for loop but it…
Zako
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Crop half of an image in OpenCV

How can I crop an image and only keep the bottom half of it? I tried: Mat cropped frame = frame(Rect(frame.cols/2, 0, frame.cols, frame.rows/2)); but it gives me an error. I also tried: double min, max; Point min_loc, max_loc; minMaxLoc(frame,…
shjnlee
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How to to find location (ROI) of a recognized object in tensorflow

I was using the tensorflow android example which has a placeholder for the location of a ROI (see tensorflow/examples/android/src/.../Classifier.java), but it is not used. I would like to be able to locate the ROI of the classified object. I…
Shari Vedovato
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Getting ROI from a Circle/Point

I have two points in an image, centre left eye (X, Y) and centre right eye (X, Y). I have drawn circles around both eyes using cv::circle, and this is fine. But what I'm now trying to do is get the ROI of the circles I've drawn, i.e. extract the…
LKB
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How to convert Color of a Rectangle (ROI) in a matrix with OpenCV Java?

I'm trying to convert a color in a ROI of an matrix with OpenCV Java with following Code public Mat detect(Mat image){ Rect roi = new Rect(new Point(50, 50), new Point(image.width() - 50, image.height() - 50)); Mat mask = image.submat(roi); …
Meldamos
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Region of Interest in Video File

This is my first time posting here and hoping for a positive result since my research is near its conclusion. I want to add in my code a function that will process only the defined region of interest of a video file. (I can't post image since I…
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how to extract the objects inside the region of interest in matlab

I am interested in extracting the objects inside the region. For example, Fig1 showed the intensity profile of my laser profile. According to the laser intensity, I divide the profile into 2 region of interest (ROI1 and ROI2). Fig2 showed the…
tytamu
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OpenCV extract area of an image from a vector of squares

I have an image that contains a square, and I need to extract the area contained in that square. After applying the squares.c script (available in the samples of every OpenCV distribution) I obtain a vector of squares, then I need to save an image…
Marco L.
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