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

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Opencv circle detection android

Goodmorning, I have to do a circle detection with android studio using opencv, i follow the example find in internet but it didn't work and i don't understand why, i'm new of android. Can someone help ...
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23 views

Detecting a smooth boundary with known shape in an image

I have designed a surface with a shape like a rounded rectangle and I want to detect its exact boundaries in a photo I take from it. A sample photo is like this: I have tried thresholding the image ...
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Difference between cv::subtract and operator - in cv::Mat OpenCV

What's the difference between cv::subtract and operator - in OpenCV? Mat original = imread...; Mat smoothed, difference, result; smoothed - original image ...
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27 views

2D Log-Gabor implementation in C++?

Is there anywhere out there a 2D log-gabor implemenataion in C++? I have been searching all day and I just couldn't find a normal implementation. I just want to test the filter in my prgoram and I ...
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27 views

Mat and int are incompatible? [closed]

anybody knows what this is? Mat mat = (Mat_<double>(3, 4) << 0, 0, width, width, 0, height, height, 0, 1, 1, 1, 1); I dont know what mat would be in ...
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47 views

How to find the actual size of an existing object from the pixels of an image?

I am quite new to vision and OpenCV, so forgive me if this is a stupid question but I have got really confused. My aim is to detect an object in an image and estimate its actual size. Assume for now ...
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48 views

Segmenting and labeling chessboards through computer vision

With almost no experience/knowledge in computer vision, I am currently trying to segment and label the separate squares on a chessboard (i.e. a1 ... h8). My goal is to use the information to ...
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1answer
121 views

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 ...
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18 views

Get a single line representations for multiple close by lines clustered together in opencv

I detected lines in an image and drew them in a separate image file in OpenCv C++. Following is a part of it. There are actually hundreds of small and thin lines which form a big single line. But I ...
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48 views

mathematical transfer for different camera attributes

Suppose I have two camera shoots(Image1,Image2) for the exactly same scene (each pixel is alignment correctly) but from different cameras and different light conditions. I want to remove this light ...
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66 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 ...
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37 views

Deriche recursive filter using OpenCV

Is it possible to create a Deriche recursive filter using opencv (the Deriche filter is a blur that minimizes noise and preserves edges for later edge detection)? I can create one using CPU code, but ...
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38 views

Getting blobs from similar colored contours in grayscale image

I want to select the staff lines as individual blobs in either of these images: Is this possible?
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113 views

Tracking a ball (using EmguCV)

I've got a video of a ball, I've done background subtraction (using MOG2) to isolate the change in the image. And I'm performing a blur to remove some of the noise caused by light/shadows/etc. So, ...
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1answer
110 views

K-means for 2D point clustering in python

I have a set of points(2D) whose pixels are set and want to perform k-means on these pixels. Is clustering the 2D coordinates the right way ? If so, can that be done using any libraries in python ?
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18 views

Eliminate frames with high reflection

I have online camera stream and want to eliminate frames with high reflection like this for example: The constraints are : Real-time no more than 2-3 mSec on Mobile Non-reference : the process ...
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72 views

Reliable detection of facial feature points

What I need is a very reliable and relatively fast (video processing) way to locate facial features. I tried stasm (http://www.milbo.users.sonic.net/stasm/) and a BoRMaN ...
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49 views

Is MATLAB the best coding tool for Digital Image Processing? [duplicate]

I am a beginner. I do coding in Matlab only for image processing purpose. But my friends say it is very slow and in OpenCv I could get multiple times faster output results compared to Matlab.In basic ...
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1answer
100 views

Balance brightness and contrast between two images

I have two different images for the same object. Each one was taken from different device (scanner, mobile camera, professional camera ..etc). the process of registeration one of them to the other ...
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70 views

get convex hull of isolated shapes with openCV/C++

I have segmented CT images, something like the following one: I would like to get a convex hull that contains all the white regions. Something like this circle, but more fitting, and of course not ...
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2answers
71 views

cause of adaptive threshold poor result

I try to run text cleaning process based on the camera captured image. By using OpenCV adaptive threshold method with parameter ...
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2answers
122 views

Median filter algorithm in opencv

I was wondering about the implementation of the Median Filter in opencv because I am suffering form its slowness. So, I intend to implement another one on my own but first I want to make sure about ...
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2answers
136 views

Finding the Harmonics contained in an Image?

I am beginer in image processing. Any signal whether it is 1D,2D or any multidimensional signal can be represented using combination of number of sine and cosine wavesforms (harmonics). Similerly any ...
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29 views

Finger Detection on various backgrounds

I tried tracking down the finger placed in the frame. Constraints: Algorithm works in live streaming of USB Camera, so there will be a lot of background changes. Algorithms tried: Tried ...
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5answers
483 views

Noise Removal from an image using Opencv

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 ...
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2answers
141 views

Matching two very similar images

I have two images for the same object from the almost same perspective (no more than 1-2 degrees or 1-2 mm is acceptable). I want to change the perspective of one of them to match exactly the other so ...
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1answer
97 views

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

http://docs.opencv.org/doc/tutorials/imgproc/imgtrans/hough_circle/hough_circle.html I'm using houghcircle function to detect circle.Problem is if i set minimum radius to null it detects wrong center ...
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170 views

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 ...
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205 views

How to detect all the connected neighboring pixels which have same color value in opencv

I should be able to input a pixel position and get all the same coloured(in my case it should be black) pixels which are connected to it. How to do this in opencv with c++. Simply the output pixels ...
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182 views

regionprops vs. findContours doesn't find the same contours

Is there a way to get the same results for cDist=regionprops(bwImg, 'Area'); and openCV's findContours? Here is what I have tried so far: ...
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1answer
142 views

Isolate the non blurred part of foucsed image

I have an image taken by a mobile phone camera with focus on a part of it let say a face or whatever. I want to know -approximately- where is the focused area. For example, a bounding box around the ...
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29 views

Hue out of range

I don't why.. but for some reason is my histogram showing that the max hue value of my image is around 339498 which doesn't make sense for me.. I am trying to create a mask, that recognizes the ...
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1answer
194 views

How to calculate the luminance of an image?

Is there any method for calculating luminance of an image? As from wiki got to know Luminance is an amount of energy perceived by the observer and LUX is different from brightness. But still is ...
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56 views

snr calculation of frame

I have to calculate SNR of an image. I have camera through which continuous images are getting generated, my requirement is to calculate the SNR in db for each image. I have seen lot of the examples ...
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20 views

Coherence of specific area of an image

I have to detect an object in an image. The manner that I am using gives me a number of possible areas of the image that may contain the object. I want to check which is the most coherence area of ...
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41 views

Primitive Feature Detection

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 ...
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2answers
348 views

Skew detection and correction using Fourier transform

I was trying to implement skew correction method for scanned documents using the method described in this paper. The algorithm steps: 1- Threshold the image . 2- Find the fourier transform. 3- ...
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2answers
90 views

Removing the 'red' artifact from my JPEG

I have a JPEG that originally came from a IP Camera. I have converted the JPEG to a bytes and have uploaded it to my server. Upon receiving it on my server I save it to disk. When I view the image it ...
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101 views

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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75 views

contour matching

Im am trying to extract contours from an image and match them with a list of contours I already have. The contours in the image are surrounded by a large black/dark rectangle. Here are the steps I ...
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1answer
551 views

Circle detection opencv

I Would like an explanation of the parameters for opencv's HoughCircles function. I'm new to image processing in general and I have recently started using opencv. ...
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286 views

DFT and Inverse DFT in Image Processing

I have implemented DFT from this link. 1) Tried taking dft for the three Channels(R, G and B) and reconstructed the original image by taking inverse dft for all three channels and merged them ...
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67 views

Non-maxima suppression of gradient image

I'm new to image processing, However I was trying to learn how to detect edges using Sobel filter I had obtained the image gradient in both X and Y directions successfully using Emgu built in ...
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81 views

How to compute Gradient of an image with kernel in python

Using python numpy or scipy I am trying to perform cross-correlation on each pixel of an image using a 3 dimensional kernel. I am more interested in looping into each pixel and applying the kernel ...
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30 views

Measuring contrast of a jpeg

I am knew to image processing. I am using Emgu C# I want to somehow measure the contrast of an image. It would be enough for my purposes to say ImageA has more contrast than ImageB. I have spent ...
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2answers
142 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 ...
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39 views

How do I deal with occlusion, warping, or perspective distortion for object detection

I am using SIFT features for detecting logos in clothes. SIFT is quite powerful, as it is scale invariant, but how do I deal with the problem of occlusion and warping? More specifically, the logos in ...
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41 views

Creating a texture image from existing image

I have some unusual question. I have searched online and couldn't find something similar to what I want to achieve. I have an image, and I want to create a new image from it (in the same size), so ...
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27 views

what are moments?

Hello all I'm using opencv after using findcontours I apply moments here is the vague wiki definition - http://en.wikipedia.org/wiki/Image_moment Can someone please explain in simpler words - ...
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106 views

Is this image good enough for OCR?

Hello I'm trying to ocr on a special image. I've done adaptive threshold , polartocartesian transformation. this is my original image this is adaptive threshold this is polartocartesian ...