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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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Computing cross-correlation of two images using OpenCV

I have a program that uses OpenCV to compute either the convolution or cross-correlation of an image with a specified kernel. I compute cross-correlation by setting the conjB flag to true when calling ...
orodbhen's user avatar
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1 answer
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Online boosting (training on the fly) for face detection

I want to implement an on-the-fly training process for face detection. I'm not sure but it seems it's called online boosting. Вefore, I have used OpenCV face detection with my own cascades, but I'm ...
mrgloom's user avatar
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5 answers
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Noise Removal from an Image Using OpenCV (Comparison to Neat Image)

I tried removing noise from the image shown below using Median Blur in OpenCV. But i'm not able to remove the colour noise completely as it is done in Neat Image. Any suggestions.? 1. Original Input ...
OpenCV User's user avatar
5 votes
3 answers
4k views

How to remove text region in a document image? or extract image from a document image

Given a document image (i.e. newspaper), how to extract photos in it or remove text region? I think traditional OCR methods may not be suitable here, as I don't need to recognize the text, and OCR is ...
kim's user avatar
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5 votes
1 answer
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Gaussian Equivalent of Convolving an Image 50 Times with a Box Filter

I have a image that I'm convolving 50 times with a box filter, and I like to replace this with a single gaussian filter. Because both box filter and gaussian filter are separable I can just study the ...
user8469759's user avatar
5 votes
2 answers
1k views

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 ...
The Beast's user avatar
  • 151
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2 answers
2k views

Face Detection + Cropping

Project: Face Detection Description: I want to detect and crop a face in an image. The image is captured through webcam and only one face per image.I used OpenCV face detector, but I was not ...
user1317084's user avatar
5 votes
1 answer
379 views

How to detect rectangular images inserted into another image?

It's just for a simple binary classification, so it's not needed to find the location of the inserted image or the content. I'm only interested in checking whether something like that is present or ...
Tobias Hermann's user avatar
5 votes
2 answers
5k views

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 ...
Tyler Roesler's user avatar
5 votes
1 answer
2k views

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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5 votes
1 answer
2k views

Obtain motion between image features by means of the homography matrix

I have been reading several really good answers about how to obtain camera pose (rotation, translation, etc), such as this one and this one, but I am not sure how this applies to my problem. My ...
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1k views

Is rotation of a Fourier transform the same thing as Fourier transform of a rotation?

I'm working on an image processing problem and wondering if DFT(rotation(image)) == rotation(DFT(image)) (1). My final goal is to apply rotations in the Fourier domain then do an inverse Fourier ...
Soltius's user avatar
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190 views

Red eye detection [closed]

Project: Red eye detection Description: I want to remove red-eye from images. I am not able to use face detector because, the faces in the images are not always frontal and also the images are of ...
user1317084's user avatar
4 votes
1 answer
4k views

Wavelength filter with OpenCV

I am new to OpenCV and DSP. I want to code a filter which act like a real optical filter. When you filter the image, the output looks like shotted with a $550nm$ optical filter lens. Like a Bandpass ...
juds's user avatar
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2 answers
10k views

Licence plate detection with different backgrounds

I just studied the Algorithm of ANPR (Automatic Number Plate Recognition) from the chp 5 of book Packtpub.Mastering.OpenCV.with.Practical.Computer.Vision.Projects in which they detect the vehicle ...
ARG's user avatar
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1 answer
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Corner detection using Chris Harris & Mike Stephens [duplicate]

I am not able to understand the formula, What is $W$ (window) and intensity in the formula mean, I found this formula in opencv doc http://docs.opencv.org/trunk/doc/py_tutorials/py_feature2d/...
Madan Ram's user avatar
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3 answers
1k views

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 ...
Rafał Hrabia's user avatar
4 votes
1 answer
842 views

Feature Detection on a Circular Metal Surface for Character Recognition

Hello I'm trying to recognize characters on the circular metal surface. Without any preprocessing I could match cropped features with original image. I've actually cropped 2 characters together to ...
Anar Bayramov's user avatar
4 votes
1 answer
2k views

Binary descriptors

I'm using an algorithm to detect interest points in an image and get their descriptor. The most recent algorithms use binary strings instead of float vectors to dramatically increase the performance ...
Rafael Soledade Matos's user avatar
4 votes
3 answers
226 views

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 ...
user297850's user avatar
4 votes
1 answer
5k views

Outlined text extraction from image using OpenCV

I have some video frames I'd like to extract some text from (for making softsubs from hardsubbed video for learning). The text in question is mostly in Chinese script (some numbers and Latin letters) ...
diwhyyyyy's user avatar
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4 votes
2 answers
26k views

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 ...
Aapan Mutsuddy's user avatar
4 votes
3 answers
2k views

Vein extraction from this image

I have this image: What methods should I use to extract the veins from this image. Thank you.
Boogami's user avatar
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4 votes
2 answers
4k views

blur detection using opencv

I'm writing a script to detect blur images using OpenCV by applying Laplacian filter and calculate the std but there is a problem the std for images that contain motion blur is very close to those ...
noura_7ussein's user avatar
4 votes
1 answer
584 views

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. ...
Quevun's user avatar
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4 votes
1 answer
623 views

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 ...
user8469759's user avatar
4 votes
2 answers
4k views

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 ...
ANIRUDH NJ's user avatar
4 votes
1 answer
2k views

Detecting defects/differences in printed images

I've been experimenting with various methods to detect defects in printed images. Features that are qualified as defects may include scratches, discoloration, etc. I'm not very experienced in image ...
40pro's user avatar
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4 votes
1 answer
2k views

what is the starting point of a contour as given by cvConvexityDefect() function in OpenCV

i have to distinguish between palm and elbow in my contour(I'm using cvconvexitydefect for that purpose). Here's the image: I'm taking contour of left image. the 2 topmost points in right image are ...
Roney Island's user avatar
4 votes
1 answer
770 views

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. ...
user67438's user avatar
4 votes
1 answer
542 views

How to Remove Double Lines Detected Along the Edges by Edge Detector?

I'm trying to take real time input for hand gestures with web cam, then processing the images to feed them to a neural network. I wrote this processing function to make the hand features look ...
Debbie's user avatar
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1 answer
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Image Gradient: Light to Dark, Dark to Light

From link: Black-to-White transition is taken as Positive slope (it has a positive value) while White-to-Black transition is taken as a Negative slope (It has negative value). So when you ...
Mandar's user avatar
  • 141
4 votes
2 answers
5k views

Metal Defect Detection

I am developing a machine vision project to find defects on metal surfaces. I want to learn and implement algorithms which commercial systems are use for metal surface defect. My sample object as ...
twister's user avatar
  • 141
4 votes
2 answers
828 views

How to Create Image Editing Filters

I am trying to make filters for days but now I just want to know the experience of others rather than go on to wrong way and finally decided to put my query over ...
ARG's user avatar
  • 601
4 votes
1 answer
319 views

remove spatial sinusoid noise from 2d image

Given a 2D image where each row of pixels is shifted by some amount horizontally in a sinusoid fashion, is it possible to recover the original image? Imagine a camera that can capture one row at a ...
HugoRune's user avatar
  • 141
4 votes
1 answer
83 views

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 ...
RedYoel's user avatar
  • 141
4 votes
1 answer
591 views

How to Find the Probability of Kalman Filter States?

I am working on a video object tracking problem. I am using Kalman filter to predict and correct the object position return by an algorithm such as CamShift. I want to adjust the likelihood ...
Dr. Strange's user avatar
4 votes
2 answers
986 views

Qualitative Evaluation of Interest-Point-Detectors and Descriptors in Computer Vision

I'm writing on a qualitative evaluation study of interest-point-detectors and descriptors. I've read all Mikolajczyk papers as well as most of the surves from Datta et al. etc. Now I'm implementing an ...
Mr.Mountain's user avatar
4 votes
0 answers
1k views

OpenCV face recognition: Finding a best match

I am working on OpenCV2.4.2 C++ interface for face recognition functionality. The face recognition feature seems to be working fine on standard databases. (AT&T, Face Recognition Data, University ...
Trupti's user avatar
  • 41
4 votes
1 answer
641 views

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(...
User4680's user avatar
3 votes
2 answers
22k views

In opecv function Hough circles how does parameter 1 and 2 affect circle detection and how can I adjust them to increase accuracy?

I'm using opencv houghcircle function to detect circles. http://docs.opencv.org/doc/tutorials/imgproc/imgtrans/hough_circle/hough_circle.html Problem is if I set minimum radius to null it detects ...
Gaurav pawar's user avatar
3 votes
2 answers
367 views

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 ...
SaulGoodMan's user avatar
3 votes
3 answers
23k views

Split and Merge image segmentation algorithm in OpenCV

I asked google and I've tried to find something in the API of OpenCV, but hadn't any good hints on split and merge image segmentation method. I want to test it, if it's working better than my ...
mchlfchr's user avatar
  • 587
3 votes
1 answer
10k views

EmguCV: Detect a ball in the frame

I am having a VERY hard time capturing when the ball comes into frame in this video http://www.youtube.com/watch?v=x1V6_OHrXIo I have no idea what to set the parameters too, and trying random values ...
CaffGeek's user avatar
  • 131
3 votes
1 answer
3k views

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 ...
Konchog's user avatar
  • 161
3 votes
2 answers
2k views

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 ...
Jim's user avatar
  • 131
3 votes
1 answer
4k views

NORM_HAMMING2 vs NORM_HAMMING

I'm trying to use ORB features with a cv::BFMatcher. ORB is based on binary descriptors so HAMMING must be the choice, but I'm not sure I understand the difference ...
Albert Garcias Mirabent's user avatar
3 votes
1 answer
606 views

Color Tracking a Red Laser Height

I'm making a Laser Harp. The application needs the position of the hand along each of the laser beams to modulate a sound synthesis or modify the properties of a sampled instrument. I'm wondering if ...
Ventolinmono's user avatar
3 votes
2 answers
5k views

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): ...
mrgloom's user avatar
  • 560
3 votes
2 answers
6k views

How to remove noise from this image without causing the crack to 'shrink'?

I am currently embarking on an image processing project to detect cracks on surfaces using OpenCV and Visual Studio via C++. I have tried writing my program and at the moment, I am stuck because I ...
galaxy_twirl's user avatar

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