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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roipoly matlab function equivalent in OpenCV

I am converting a matlab code into C++ using OpenCV libraries. Can anyone tell me roipoly matlab function equivalent in OpenCV?? Or how to get the same functionality using OpenCV? BW = roipoly(I, c, r) BW = roipoly(I, c, r) returns the ROI…
2vision2
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Deform points in a plane

Point :: (x y) is known. I have points inside a triangular region. I know the coordinates of the vertices in initial and final positions. I know the initial coordinates of all the points inside the triangular region. Now I want to find out the…
2vision2
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C# polygon to mask?

I have x, y coordinates of all vertices of a polygon, say (1,1) (20,10) (10,30), how do I generate a mask with all pixels inside the polygon being 1 whereas outside being 0? I know there is a function FillPolygon() in C# that looks pretty much doing…
Nick Tsui
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Measuring Intensity Using ImageJ

we have to measure the intensity of the fluorescence in certain regions of images using imagej. we came up with the below steps to measure the intensity. while it does seem correct, my question is --> are we actually measuring intensity correctly…
user1911720
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Android-OpenCV Warp ROI

How can I warp a rectangular extracted ROI so that it fills the entire preview keeping proportions? I extracted a rectangular from the camera source image (Opencv Mat) and I saved into another Mat. Now I'd like to warp/zoom/enlarge/I don't know ...…
net.cat
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How can I set the position of a IMFREEHAND handles in MATLAB?

I save a given position array and handle object defined by IMFREEHAND. After loading this data back to workspace I want to set this IMFREEHAND object again to the specified position analogous to i.e. IMRECT where I can set the position via…
schiba
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Nextag ROI optimizer code for woo commerce. How do I remove the # sign from my order number?

Hi I am trying to install the Nextag ROI optimizer code from Nextag into my woocommerce theme/plugin. (thankyou.php template) It is working except I cannot get rid of the # symbol in the final output. The Nextag stats will not show my order numbers…
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Auto vectorization Region of interest (crop)

I have a library which has some image processing algorithms including a Region of Interest (crop) algorithm. When compiling with GCC, the auto vectorizer speeds up a lot of the code but worsens the performance of the Crop algorithm. Is there a way…
illumi
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OpenCV getRectSubPix with Alpha Channel

I need to use the getRectSubPix function in my code as part of a process of cropping an rotating a section of my image. This works fine normally with 3 channel images, but as soon as I try to use it with a BGRA or a RGBA mat image it crashes saying…
blorgggg
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Get a array mask for an image from a polygon shaped ROI

i am trying to make an polygon ROI for an matplotlib imshow(image). Using the Event Handling of matplotlib i am able to manually set an polygon ROI ontop of the image (via Line2D segments). The result is a set of edge coordinates (in pixel values)…
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Setting Polygon ROI with mouse in Qt

Anyone have any idea how I can implement this? I'd like to have a function basically exactly like impoly in matlab or the "polygon sections" tool in imageJ, where you click to form a polygonal section and then each node can be adjusted, etc. I'd…
JustinBlaber
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cvSetImageROI using greyscale and color images

I'm trying to set an image region of interest and add one image into another. One image is a mask (greyscale) and the other one is a color image. Right now, I'm doing IplImage * _newImg = newImage.getCvImage(); IplImage * _oldBG =…
minimalpop
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drawing a rectangle on an image after identifying the area using ROI (OpenCV)

I am trying to use the function ROI in OpenCV to identify a contour, later .. in that ROI I am identifying a specific color.. so I want to draw rectangle or circle around this shape but in the original image .. the problem that the location I am…
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Image Processing method for "spiky" selection

I have an input as a 3D binary image and the preferred output below: Input: Preferred Output: What image processing methods should I look for if I am to have only the spiky object(s) remain, just like the preferred output above?
Karl
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how to open some region from a compressed image file not loading full image file into memory?

We had an image loaded into open CV from some compressed JPG or PNG file. It was really big. We had some ROI on it say from (2000:2000) to (2100:2100) (square 100x100). We closed an image. Could we any how open that ROI again not loading full image…
myWallJSON
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