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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Skewed rectified aerial images
I have a series of aerial images from which I would like to get disparity maps for every consequent pair. In order to do that I do a stereo rectification.
The problem is that sometimes rectified ...
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Redistributing Color in a RGB Image According to a Gaussian Distribution
I haven't done this stuff in a while.
If I have an image $I$ I can equalize the histogram of the image using some opencv procedure, it's already defined. Equalizing an histogram means essentially to ...
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Fitting a gaussian image using opencv
I'm reading through the opencv documentation and some questions in SO but it doesn't seem to provide this information.
I've an image $I(x,y)$ and I want to find a gaussian function $f_{\mu,\Sigma}(x,...
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Pattern recognition
I am new to the world of computer vision, so please excuse my basic questions.
I have two patterns: one consisting of a single circle of radius $r$, and one made of several circles, still of radius $...
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Line Detection with OpenCV and Python [closed]
Why do we get less amount of lines then desired in line detection using HoughLines tranformation from OpenCV? How could we improve this method and get all the lines appearing in the image? I would ...
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Manipulating RGB color by copying channel value
I have a picture and trying to swap the RGB channel into RRB, it's like I need to change all G pixels value into R. I did that by copying the R pixel value to G and store it into a new image file (Mat)...
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Given a set of lines, find only those who are parallel (perspective)
I have an image which includes straight borders which I need to detect:
The borders are thick, which causes hough transform to detect multiple lines for each border, as can be seen in the following ...
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Image Shadow Removal Using OpenCV and Python
How do I remove a shadow after MOG2 background subtraction using OpenCV Python? I used all morphological operations, gaussian and median blur, thresholding. it removes noises but deep shadow is ...
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How to detect curve in chart grid?
I would like to detect a curve in a grid. Example (hand-drawn):
https://i.stack.imgur.com/LSLUx.jpg
I would like to detect the intersects of the curve with the vertical gridlines marked with the "x" ...
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Why entropy is undefined in low contrast image
I am trying to measure contrast of image by entropy of histogram of image.
Code for computing entropy
...
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Calculating distance between two blobs in a binary image in microns
I have a monochrome CCD camera with resolution 960 X 1280 and can give up-to 15 fps
I am working on python opencv.
I want to track the distance between two rectangular blobs in binary images in real ...
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Obtaining Subpixel Resolution for Video Processing in Python
I am working on a video processing application to calculate distance between two points using opencv
Specs :
Linear Pixels - 1600.
FOV - 100 mm
Resolution per pixel using above data : 62 micron
...
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How to choose good features for my machine vision application? [closed]
I am trying to create an application (with OpenCV3) that can distinguish sidewalks from streets by a real-time camera that is embedded in a glass. I have 3 question about this project:
Which features ...
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Does the cv2.waitKey argument determine the frame-rate while capturing a video?
Kinda new to image processing, so pardon me if the question is too stupid.
Using the library cv2 in python to capture video from my webcam, which, so far as I can see as a programmer, is basically ...
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Improving Template Matching Algorithm for OpenCV
Car detection using OpenCV
I am working on a small personal project where i have to know wether an image shown is a car or not. I am using the basic OpenCV python based template matching.
Positive ...
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computer vision - How to correctly calibrate my camera with a wide angle lens using openCV?
I am trying to calibrate a camera with a fisheye lens. I therefor used the fisheye lens module, but keep getting strange results no matter what distortion parameters I fix.
This is the input image I ...
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Determining the pattern direction of a bitmap image
How can I obtain average direction of the pattern shown in the figure below. It is the direction of the red arrow relative to the yellow (horizontal) line. Any ideas for an approach? I couldn't figure ...
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homomorphic filter - python overflow
I'm trying to implement the homomorphic filtering as implemented by this research article - step 4 (pdf)
The original Matlab code, which I'm trying to translate into Python, is as follows (WARNING: ...
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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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OpenCV denoising a 3x3 pixel pattern noise
This picture
shows two photos captured by a camera from a black photographic paper. The cross is marked by laser. The left one shows a 9 pixel pattern of noise.
This gets in the way of auto-focus ...
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stones' detection in jewel image
The project I am doing is to detect stones in an image of a jewel, so as to get the idea of the deduction to be made in the gross weight of the jewel.
I have done image-segmentation in the HSV color ...
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Bit plane slicing in python
I recently came across a technique called bit-plane slicing for image
compression in a book "Digital image processing" by gonzalez and woods . They
just presented the theory and i wanted to ...
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Correct Fish Eye camera Radial Distortion and blurry effect at the image edges
There are a lot of questions regarding this topic ,but I am trying to get a more clear picture from these questions.
I am trying to calibrate a fish eye camera and I am using OpenCV omnidir class ...
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Distance from an object.. Where is the camera origine?
I compute the distance from an object (Chessboard) using OpenCv and my camera parameters using those steps:
findChessboardCorners
solvePnP
->Distance
The distance I get is between two points: the ...
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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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Opencv color segmentation of traffic signs: HSV ranges
I am working on a project to detect and recognize signs in images from the LISA Traffic Sign Dataset. Since the images are very noisy (in regard to background) I am trying to segment the signs based ...
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How to reliably detect the state (opened or closed) of sliding doors from a statically-positioned video stream
I have a mounted (static) camera that has a view of a set of sliding doors. Since doors are rectangular in nature, and they don't have many degrees of freedom, this seems like a problem that should ...
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library for computing differential signatures from 2D planar curves
For one of the lectures on 2D planar differential geometry in the series "Image and Video Processing: From Mars to Hollywood With a Stop at The Hospital", the lecturer discusses differential ...
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Convolution of Two Kernels [OpenCV]
I've been completely stuck on a portion of my assignment for a few days now. After plenty of searching around, I have been unsuccessful in discovering information that leads me to the correct solution....
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How can I isolate a Hough circle that I perceive to be the best fit, but is ranked much lower?
I am working on finding the center and radius of a laser spot, which I plan on doing by using the HoughCircle algorithm in opencv 3.2 for Visual C++.
One of my sample images is a very well defined ...
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Find a small image pattern in another similar image
I have this pattern in the first image which I want to find in the second image. However the two images are totally different so I just need to find the closest set of indices where these two images ...
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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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OpenCV - What type of a result does cv2.goodFeaturesToTrack() return?
Dear citizens of Stackexchange,
I am a 3rd grade Electrical and Electronics Engineer student, who is working on an image processing project using OpenCV 3.2 and Python 2.7.
What we would like to ...
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Techniques for detecting small blobs in noisy images
I am trying to write a program that uses computer vision techniques to detect (and track) tiny blobs in a stream of very noisy images. My data is of two types: one set of images are not so noisy, ...
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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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OpenCV camshift algorithm
I got a lab report to make in an image processing course in my university, and I was asked a question about the OpenCV camshift algorithm (for video tracking):
the camshift algorithm works on the hue ...
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the position of image plane in optical imaging
In the book Learning OpenCV, there is one figure that show the image plane always is focal image.
The description of the figure from the book is as follow.
We begin by looking at the simplest model ...
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How to recognize an object from a small training set of images?
Given a small training set of images (say, around 6 max) of the same object, how to measure how likely is another query image to contain the given object?
The training images are "clean", i.e. only ...
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camera movement calculation
I'm trying to work out how to estimate camera movement between 2 equirectangular photos (static scenes indoor). Both photos are taken with the same camera (Ricoh Theta S) on the tripod. Height of the ...
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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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ICY feature detector and edge detector in opencv
I need to trace the internal feature boundaries of blobs (blood cells) in OpenCV to train a classifier.
As a good reference from ICY in java, the following sequence of operations gives good, ...
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Summed-area table vs Integral image?
I have been going through few research papers around face recognition and I came across two texture extraction algorithms :
Summed-area table by Crow et al. ("Summed-area tables for texture mapping",...
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Line Detection with OpenCV
I'm trying to use the native functions of OpenCV HoughLines and HoughLinesP to detect the lines from an image. The Canny edge output of that image is the folllowing:
The problem is that the OpenCV ...
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Removing a darkened caption with text on it in an image
Image processing is new for me, so forgive me if my question sounds vague.
I'll try to supplement it with what I have learned until now and also a couple of images.
See the caption in the image ...
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Comparison between watershed and grabcut
I know that watershed and grabcut algorithms are both common tools for image segmentation. They both seem to rely on predefined markers to form something like a source-sink system and then uses the ...
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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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How to Get Rid of Ripples from a Gradient Image of a Smoothed Image?
I have a gray scale UINT8 image. When I smooth it with a Gaussian filter and then compute the gradient image with a Sobel filter in OpenCV, ripples would appear.
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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 ...
user67664
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Practical advices for applying phase correlation in image registration task
I'm using OpenCV to detect shift between 2 images, here is sample code (based on cv::phaseCorrelate function):
...
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How to get Harris corners that are present in watershed segmented Bitwise image(road part)?
This is Harris corner image of test image:
This is Bitwise watershed segmented image:
I want to get that Harris corners which will be in segmented part of image(road part).
