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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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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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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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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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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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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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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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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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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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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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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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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What Is the Cause for Poor Results with Adaptive Thresholding?
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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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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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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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 ...
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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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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 ...
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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 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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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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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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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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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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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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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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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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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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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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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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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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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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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 ...
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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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How to choose suitable segmentation process for image processing
Hello I'm new on image processing.
I know there are a lot of threshold and region growing algorithms to use.
But I would like to know what is the trick for choosing suitable method for an image ?
...
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How to remove the noise without destroying the main edge?
I am working on a project. I want to segment a logo from a car and the picture's size is 3648*2432. The logo is selected by the red rectangle.
I extracted this area and turn into gray level. The ...
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Is it possible to hack camera calibration without having access to the camera?
Many times we have a stream of video to process without access to camera. Having access to camera matrix would be beneficial for various processing techniques. Is it possible to hack camera ...
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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 ...
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OpenCV Motion Analysis: Optical Flow vs Motion History
OpenCV Motion Analysis Documentation lists multiple techniques for motion tracking:
Sparse Optical Flow | calcOpticalFlowPyrLK,
Dense Optical Flow | calcOpticalFlowFarneback, and
Motion History ...
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How to detect the exception by SVM with openCV
I have implemented SVM by openCV. However, I have a problem about SVM with openCV. For example, I have six categories, but I just use "five" of them to train my SVM. When testing, I want my system ...
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Why Normalized Cross Correlation Score of different templates is high?
I am using OpenCv's built in template matching function to search for an object in image. I am using Normalized Cross Correlation Method.The function is returning a value which I think indication of ...
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Shape recognition, hough transform
I'm trying to match a picture saying "this is ducks, this is towers" by giving votes from the hough transform of a picture.
I've found this article http://ttic.uchicago.edu/~smaji/papers/hough-...
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Does accurate translation estimation using a camera matrix mean the orientation estimation will also be accurate?
Pose Estimation of single camera and planar pattern:
If I have an appropriate camera matrix with intrinsic parameters that allows me to calculate translation of the camera relative to a chessboard, ...
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Detecting text lines in image by means of Hough Transform
In my Android App,I have to detect text lines in images.I want to use Hough Transform to detect lines.You can see an image below:
I got edges in image by ...
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Skeleton from distance map
Can anyone give some tips how to obtain Skeleton from distance map?
I already managed to obtain skeleton using erased method (e.g. zhang suen) but it's time consuming because it's an iterative method ...
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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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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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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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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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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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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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