OpenCV (Open Source Computer Vision) is a cross-platform library of programming functions for real time computer vision.

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Finding local brightness maximas with OpenCV

I want to find points (of a processed image) that are the brightest in their local region. Basically, I want all of the points whose 8 neighbors are all smaller but I want to have brighter maxima ...
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1answer
16 views

Is a change in colorspace needed when comparing colors only evaluated by the computer?

I am confused about the need to change color space for color comparison. I have read about delta E, the Lab format, and I do understand that comparisons in the RGB color space will not seem ...
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Get the number of objects from the edges (opencv 4 android)

I would like to get the count of objects in an image based on the number of edges drawn using the mat. Steps followed include: Capture image convert to grayscale Blur the image like ...
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37 views

Why is LBP generaly faster than HAAR?

I am digging into Haar like and LBP features. More precisely its implementation in OpenCV. Every article or forum entry I found states, that LBP is faster than Haar. My local tests also confirm this ...
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53 views

Template matching or object recognition?

Problem: I have a photo of an object (a manufactured part like the attached photo below), using my Andoird phone camera I want to verify if the object in camera preview matches to the template or not. ...
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14 views

Problem in openCV casade classifier

I am trying to train cascade classifier using "opencv_traincascade" utility. I'm having 100 positive images and 500 negative images. I have created .vec file using following command: ...
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23 views

High triangulation error

I have implemented a 2D->3D point triangulation method, which uses 2 poses P1 and P2 and 2 points back-projected to z=1 point1 and point2 to recover depth: ...
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17 views

State of the art post processing techniques for segmented images

I've been working on grabcut-based approaches to human segmentation in images. I've combined colour, motion and face detection cues to provide some seeds and perform a grabcut. While the results have ...
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38 views

Visual regression test - Extract elements of GUI-Screenshot - MSER OpenCV

For a visual regression test I need to compare screenshots of webpages (different release-versions). I started with pixel by pixel compare. Actually I split the screenshot in different parts (maybe ...
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1answer
45 views

Using ROC curves for comparing the performance of SIFT and SURF

I want to compare the performance of SIFT and SURF against some standard image set. After a bit of research, I found that ROC curves are one of the best ways to do this task. In order to plot ROC ...
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1answer
114 views

Zernike Moments' implementation in OpenCV

The reason why Hu moments were implemented in OpenCV and why Zernike moments were not implemented is looking like their performance similar as stated in this paper. As stated in the paper Zernike ...
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116 views

MPEG-7 descriptors' implementation in OpenCV

I'm looking for implementation of MPEG-7 descriptors which are compatible with OpenCV's recent versions and containing "region-based shape descriptor ART(Angular Radial Transformation)". I ...
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2answers
62 views

Grayscale conversion before applying sobel gradient operator

I am currently replacing a hand-made image processing library by OpenCV. The programmer who worked on this library had implemented the sobel gradient function. This implementation is right except that ...
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1answer
55 views

MATLAB rand and C++ rand() [closed]

I am trying to port a MATLAB code into C++ and found the usage of rand in MATLAB. Is MATLAB's rand function and C++ ...
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18 views

OpenCV: Is NormalBayesClassifier::train function running ok?

I am have the code from here. I have changed the images with some of my own and I have seen that SVM is not working. That is not a problem because I have found on ...
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2answers
57 views

How to proceess Image with curved corners and edges to give sharp Corners?

I have several Images of shape H, F, I, L.. which have curved corners. How do I process them to give sharp right-angled corners? I tried approximating them with inner rectangles, but this takes a LOT ...
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2answers
174 views

Is it possible to convert from 2D to 3D form?

I have captured car positions at different frames from the video. Suppose car's(e.g.left side car which is coming towards us in the images) centroid at video frame1 is P(x1,y1) and Q(x2,y2) at video ...
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1answer
40 views

Detecting blobs that connects to any other blob, maybe with OpenCV

In the image, I connects to universe, but II and III not. I need to detect both II and III, also I if possible. Is it possible with current computer vision libraries?
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58 views

how to retreive descriptors from BoW dictionary and match it with query image descriptor - CBIR?

I am trying to implement Content based Image retrieval using BoW-SIFT-SVM. I succesfully created BoW codebook. In the retrieval phase how to match the query descriptor with the dictionary? i.e., how ...
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2answers
61 views

how to make 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 ...
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1answer
204 views

OpenCV Haar Classifier - best type of positive images

I'm currently collating images to try and develop a HAAR classifier using the OpenCV traincascade functionality. The objects I want to detect are small and numerous (bees), and I'm curious as to ...
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131 views

How to make color balance of photoshop using opencv

I want to make the same thing programmatically like Color balance in Photoshop , like in below image if we have same bar ...
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3answers
78 views

Trying to translate formula for blending mode

I am using OpenCV C++ for making the blending mode like in photoshop, I want to make overlay mode in it. I search its alternate in OpenCV in which I found this ...
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46 views

How vibrance method of photoshop work in opencv

Can somebody please explain how Photoshop vibrance function can use in opencv c++ ? so that I may reproduce the same effects in my application. Here is the vibrance ...
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1answer
105 views

Counting human movement of exercise using ROI or pre-set passing line with OpenCV

I'm currently doing my final year Degree in computing studies. The project I'm working on is a video of a webcam or computer webcam to have 2 pre-defined ROI (Region of Interest) on top and bottom ...
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16 views

Where can I find annotated databases of faces with profile views?

I'm working on a project that uses AAMs (Active Appearance Models). I'd like to have an AAM with profile view. Is is possible to get free annotated images of faces in a profile view?
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1answer
147 views

Histogram and binary image in opencv? [closed]

I would like to compute how many zeros and ones (e.i. 255) in a binary image. The following code to generate a binary image by using Matlab. ...
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47 views

reducing chroma of image on client and reconstructing on server

I have a C# desktop application. I am using Emgu wrapper to openCV. My objective is to upload images in the most efficient way I can. I have hit upon the idea of loading an image (jpeg) into memory ...
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252 views

Sharpening an image using emgu

I have c# desktop application and I am using emgu framework as a wrapper for OpenCV. I am trying to sharpen an image because the input images are not great. I tired a technique I found via searches ...
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1answer
94 views

How to make filters?

I am trying to make filters like sepia filter in my app like other photo editing applications , till now I don't have any idea about it , Can any one help me out ...
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2answers
377 views

Improve contrast when image has a flood of white balancing

I have an image taken a night time. I apply _EqualizeHist to it. But the result is a high level of whiteness running through the image. This is the image: I had asked this question in a slightly ...
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136 views

Motion and Distortion Estimation using multiple still images?

TL/DR: I'd like to take the median of lots of images to make a single "better" image. The problem is, the camera is slowly moving, and there is significant lens distortion. On the plus side the ...
4
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1answer
149 views

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 ...
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2answers
367 views

Refining lines in an image with openCV

So in my project I am extracting the lines of an image with openCV2 by firstly creating a skeleton: I convert it tp a binary image, invert it (to make it work with morphological operations) and then ...
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1answer
69 views

Mat class of c++ in open cv [closed]

I am a beginner in opencv and have started learning it using visual studio 2012 and opencv 2.4.7 . But i got stuck at very beginning .I want to know about Mat used in Opencv .It is a class and an ...
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95 views

Subsetting a GeoTIFF Image

I wish to create a subset of a multiband image in OpenCV / Python. The image is in the GeoTiff format. The bands might be 16 bit or 8bit. How do I achieve this using OpenCV and Python.
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945 views

Need help in panoramic image stitching using emgu cv

I am doing a project on panoramic stitching of Images using Emgu CV (Open CV for C#). Till now I have done some work that stitches images but the output is kinda weird. This is what I am getting: My ...
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1answer
143 views

Calculating an HSV histogram

I have to compute an HSV histogram of a colored image. Is it same as an H-S histogram? I have found H-S histogram computation code everywhere. What is the method to change an H-S histogram to an ...
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1answer
64 views

How to use clustering file after training

I trained the data using BOG with SVM , i trained it , now i just want to open it through xml , i don't want to train it again and again on every run , I trained ...
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2answers
1k 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 ...
3
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1answer
115 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 ...
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1answer
141 views

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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593 views

OpenCV: Problem at creating a Skeleton of Lines

I need to get the lines from a photographie of a sheet of paper. While recherching, I came along this, where one answer referred to this blog entry. Now I am having trouble with this approach. I have ...
2
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1answer
1k views

Influence of image size to edge detection in OpenCV

I need to scan an image in OpenCV and obtain the lines. For this I use the canny edge detector and then the propabilistic Hough transform, with which I actually get the lines. The problem now is that ...
3
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2answers
1k views

Why do we use keypoint descriptors?

I just studied about SURF and I'm going for its implementation, but I still didn't understand why we use descriptors. I understand what keypoints are and their purpose, but when we extract the ...
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2answers
552 views

How to recognize hexagonal tiling in boardgame?

I would like to recognize the boundaries of a hexagonal tiling in a photograph, like in image below: It seems to me, that a standard approach at a square grid is to first detect corners (e.g. ...
7
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1answer
285 views

Jigsaw puzzle: isolating the pieces (separating “stuck” blobs)

I'm new to image processing, and I'm trying to get my feet wet. I have taken a picture of some jigsaw puzzle pieces and I want to isolate the pieces. I am using the Python SimpleCV library to do ...
3
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1answer
100 views

Garment Cropping from mannequin

I have two images – mannequin with and without garment. Please refer sample images below. Ignore the jewels, footwear on the mannequin, imagine the second mannequin has only dress. I want to ...
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2answers
2k views

How to compute Image Gradients?

How to compute Image gradients? In X Direction - Kernel : -1 0 1 In Y Direction - Kernel : -1 0 1 Let's assume my input image is: unsigned char* imgImage; ...
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How can I create polygon estimates of each body part/limb that is present in an image which always contains one person?

Background I am working to identify and isolate each human limb of a known person, in pose, in an image which is relatively noisy. It should also be noted that the image is a snapshot extracted from ...