Questions tagged [opencv]
OpenCV (Open Source Computer Vision) is a cross-platform library of programming functions for real time computer vision.
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Detect GUI Buttons in every application window with python
I want to detect every buttons in every application windows.
For example, in explorer window, I want to detect every Tags, folders, files and Buttons like "page back", "page forward&...
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How to categorize the images based on Illumination / shadow?
Input: Cropped face or Non Cropped face images.
Detailed explanation: My project is face authentication. I am using OpenCV face detector to crop face from images. I am using OpenCV implementation of ...
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Hand Jitter Problem
I am currently developing algorithm using openCV C++ for implementing laser as a mouse.Currently am having an issue of hand jitters.(ie. The presenter's hand may shake unnecessarily which may cause ...
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Python - CV, contour and measurements
I have small problem with cv in Python and rhombus. I can read frame from the camera and create contours...
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Binarization of image for varying background and foreground colors for OCR
I am trying to develop an automated OCR system for images obtained from the internet. The images mostly consist of computer generated text imposed on a background, so the OCR should produce near ...
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PSNR decreases while denoising
I currently am trying to portray PSNR's ability to measure noise in an image. The PSNR is said to be high (around 40 dB) if there is a low amount of noise in the 2D signal.
In my experiment I have ...
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Detecting bullet holes using Python with camera or sensors
I am trying to build a system to detect bullet holes in paper. I've read many StackOverflow threads but not a single one satisfied me. Current methods, which I am using, are good but not perfect and ...
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Fingerprint enhancement lighter version
I've been advised to ask here, I hope that it fits.
Original question:
I want to create a more straightforward and lighter version of this fantastic repo (which itself is based on Fingerprint Image ...
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What does the last row of a homography matrix mean?
I have used the MOTION_HOMOGRAPHY function in OpenCV (python3.6, enhanced correlation coefficient) to register a pair of images, and I am trying to interpret the 3 x 3 warp matrix the function returns:...
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Efficient Hessian-Laplace blob detector implementation
As it is mentioned in a paper for SURF, it is possible to approximate hessian determinant using integral images.
If I want to implement Hessian-Laplace detector, is it feasible to also approximate ...
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Primitive Feature Detection to Detect a Black Circle within an Image
I am trying to check whether this black circle is exist or not on my images.
My current approach is like that;
Hough Circle detection
Crop the outer roi
Adaptive threshold
count zero pixels
if ...
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Is the behaviour of the following filter plausible?
I've designed a filter based on this equation
$$
E(u) = \frac{1}{2}\int_{\Omega} \left[(u-f)^2 + g(\lVert \nabla u \rVert)\right]dxdy
$$
Euler-Lagrange equations in this case are (should be) given ...
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Segment Hand Image into Palm and Fingers
Here is my code, i want to extract only the fingers and save them as a new image
...
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Shape Properties Which Are Scale Rotation Invariant Like HuMoment
There are other shape properties scale-rotation invariant except HuMoment?
There are example that show me how can i implement them?
I find this example in c++ https://stackoverflow.com/questions/...
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How can i compute perimeter and area of a skeletonized circle?
In opencv if i use findcontours function, i get contours and i can compute area, perimeter, convex hull.
if i use a Skeletonized image of a circle how can i compute perimeter,area, convex hull of the ...
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Convex Hull Area in Pixels
I am calculating different attributes for connected regions of the image, with the final goal of classification. One of the attributes I am working with is a sparsity measure, calculated as the ratio ...
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Implementing Edge Preserving Diffusion (Anisotropic Diffusion)
I am trying to implement edge preserving diffusion. Recall the general diffusion equation to be:
$$\DeclareMathOperator{\Div}{div}\delta_t u = \Div(g \nabla u)$$
Where $g$ is the speed of the ...
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Finding rectangle corners by using point cloud
I have a rectangle in the 3D scene, which I know its width and height. It is placed in the 3D scene like the image below. I can manually select all points on the rectangle by mouse click.
Given the ...
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Image processing (number recognition) woes
So I have the following image:
Using GIMP, I was able to get to here:
Select all white color (with a touch of fuzz)
Invert selection
Cut selection
Invert all color (goes black)
But now I'm stuck...
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How to detect a line from a broken line segment in video?
I am trying to detect meteors in a video, and so far, what I did.
Preprocessing: changing to grayscale and morphological operations like dilation and erosion.
background subtraction method
adding ...
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Camera sensor artifacts next to edges in calibration images; what is causing these?
I am trying to image some ChArUco targets using a monochrome machine vision camera with a CMOS sensor and the attached images show the artifact I am observing:
2-pixel-wide bright vertical streaks ...
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OpenCV 2 Connect Incomplete Contours edges
I have to connect the unfinished edges of the contours in the red color bounding box.
I used distance transform, watershed, and morphology, but still, edges are not connecting.
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Gap Filling Contours / Lines
I have the following image:
and I would like to fill in its contours (i.e. I would like to gap fill the lines in this image).
I have tried a morphological closing, but using a rectangular kernel of ...
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Looking for a way to fill holes in objects, and break bridges between them
I am trying to extract building footprints from satellite images. Using a series of morphological operations i.e erosion and opening by reconstruction, I'm able to obtain the footprints, albeit with a ...
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Laplacian Filter kernel size meaning
I'm using laplacian filter in opencv.
I usually use laplacian filter with kernel size 3 which is default setting in opencv.
I'm just curious what happen(intuitively) when I choose bigger size kernel?
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Can DFT magnitude be used to identify repeating patterns in an Image?
Given the DFT magnitude vector of an 1-D image, I want to understand if we can calculate the size and pitch of repeating patterns in the image. Is this possible? I took a few test images and ...
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OpenCV canny vs my own C++ version - high difference
I have implemented my own canny edge detector in C++. If I compare the result with the same thresholds to OpenCV (cv::Canny(img, res, 50, 100)), the difference is ...
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DFT and Inverse DFT in Image Processing
I have implemented DFT from Vision & Graphics Group at the Faculty of Informatics and Information Technologies STU - Frequency domain filtration.
Tried taking dft for the three Channels(R, G and ...
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Implementation of Wiener filter to deblur an image using Python and OpenCV
EDIT: I have debugged the runtime warning, and now I am able to get an output image. However, the output image is still blurry. Increasing the constant value heavily distorts the image. Setting ...
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Removing white reflective pixels from scanned RGB image (Python - preferably OpenCV)
The images above are tiles taken from a scanned painting. It's easy to see where there are tiny reflections scattered throughout. I wish to remove (or diminish) the tiny reflections somehow, across a ...
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Removing noisy lines from image - opencv - python
I want to process different type of image to extract actual text from noisy image .I am using open cv to do this job it is working fine but the problem is I need to set different lower threshold to ...
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Problem with "Topological Structural Analysis of Digitized Binary Images by Border Following" by Suzuki Abe
I have a Problem with the Paper "Topological Structural Analysis of Digitized Binary Images by Border Following" by Suzuki and Abe.
In the Chapter "Appendix I: The Formal Description of ...
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Which Blur is being used in this effect
I'm trying to recreate an effect used on photoshop called satin effect, which has an option that control the size of the satin, which I think it's just a special blur applied to the satin pattern
So ...
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What happens when you read and save the same JPEG image again over and over?
This question is mostly related to jpeg compression and expected results when you read and save the same jpeg file several times.
Let's say you have read an uncompressed image (originally it has never ...
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What Is the Best Color Space to Work with for Hand Detection: RGB, HSV, or YCrCb?
I'm working on hand gesture recognition using C#. I'm using OPENCV for skin detection but its performance is not optimal. So I decided to do some filtering based on color space, but I do not know what ...
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Calibration using Camera Calibration Toolbox for Matlab vs OpenCV
I am currently working to calibrate a camera and I tried using both the Caltech Camera Calibration Toolbox for Matlab and OpenCV. I used the same images for both methods. Even if the error seems to ...
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How to achieve uniform gaussian profile? Beam profile has grainy/multimode pattern
Hi apologies in advance if this (optics & image-process) is not where I should post this question. Thanks for the help!
I'm required to make a jig that measures the divergence angle of a ...
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How can I detect pipeline cracks using OpenCV and Python?
I have developed a robot that captures images of the pipeline interior as it moves. The requirement was to be able to detect cracks inside. So far i tried several OpenCV codes that find the crack ...
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What Is the Difference between Difference of Gaussian, Laplace of Gaussian, and Mexican Hat Wavelet?
There are three techniques used in CV that seem very similar to each other, but with subtle differences:
Laplacian of Gaussian: $\nabla^2\left[g(x,y,t)\ast f(x,y)\right]$
Difference of Gaussians: $ \...
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Finding Homography Matrix Using Lines
I have some Points and Lines from original image and the corresponding points and lines from top view image.
-> I tried to find homography using points
Used OpenCV function findHomography(...
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How to remove dark shadows from camera capturing when combining LED spots and ambient light
I'm getting strange moving shadow strips on my camera capture during a computer vision experiment:
As the gif image above shows, those strips move to bottom slowly. I have also noticed that it ...
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Recommended Order of Performing Denoising, Deblurring and Super Resolution on an Image
In the normal workflow of image processing, there are multiple operations, increase image contrast, image denoising, image deblur and image super-resolution. What are the sequence/order of performing ...
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How can we know the geometry of a blob detected by OpenCV
I am performing blob analysis using connectedComponentsWithStats, which returns elementary statistics about the blobs (AABB and area). It is also possible to ...
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Feature Extraction for Image Classification of Vegetables and Fruits Using Classic Computer Vision Techniques
I don't know if this is the right place to ask this but lets go. I am a beginner in computer vision and I have a project of fruit recognition based on Kaggle's Fruit 360 dataset. I know that CNNs are ...
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Opencv Android Perspective Transformation not working as expected
I'm working with perspective transformation in opencv for android for a personal project.
The thing I'd like to do is to acquire a document like CamScanner does.
For this I import a picture and let ...
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How to select the specific frame with object
I am detecting the object from the live camera through feature detection with svm , and it read every frame from camera while predicting which affect its speed , i just want that it should select the ...
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Running the BM3D Denoising Algorithm in Python
I am looking for a strong baseline in image denoising and therefore wanted to have the BM3D algorithm in my benchmark.
These 2 python implementations:
https://github.com/ericmjonas/pybm3d
https://...
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Segmentation of warped text lines
I am trying to segment warped text lines found in photos taken from a page of a book (from the camera of a smartphone). This is meant as a preprocessing step before running OCR on them.
I have found ...
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Want to do shot boundary detection via SVM, what are some good features?
I want to do shot boundary detection via SVM's.
I'm dividing the frame into nxn blocks. Per block I'm finding these features:
shannons entropy
edges (H,V,Diag)
standard deviation
for consecutive ...
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