Learn OpenCV by Examples

OpenCV simplified for beginners by the use of examples. Learn OpenCV with basic implementation of different algorithms. Please visit LearnOpenCV.com for newer articles.

Website

opencvexamples.blogspot.de · all feeds from this site

Feed URL

https://opencvexamples.blogspot.com/feeds/posts/default Copy

Follow Read it in your FeedListing reader

Or add to: Feedly Inoreader Raw feed

Latest posts

• Discrete Fourier Transform 05 Jun 2014

  The Fourier Transform will decompose an image into its sinus and cosines components. It will transform an image from its spatial domain to its frequency domain. Mathematically a two dimensional images Fourier transform is: Here f is the image value in its spatial domain and F in…

• Crop elliptical region from image 07 Feb 2014

  We know that we can represent image as a matrix, and matrix can not be elliptical. So when you want to crop a elliptical area from an image, then you have to extract the elliptical region and remove rest of the information outside the ellipse. This can be done by AND operation…

• Calculating absolute values with scaling 29 Jan 2014

  void convertScaleAbs (InputArray src, OutputArray dst, double alpha=1, double beta=0) - Scales, calculates absolute values, and converts the result to 8-bit. Parameters: src – input array. dst – output array. alpha – optional scale factor. beta – optional delta added to the…

• Window management in OpenCV 28 Jan 2014

  void namedWindow (const string&winname, int flags=WINDOW_AUTOSIZE ) Parameters: name – Name of the window in the window caption that may be used as a window identifier. flags – Flags of the window. Currently the only supported flag is CV_WINDOW_AUTOSIZE. If this is set, the…

• Perspective Transform 11 Jan 2014

  Mat getPerspectiveTransform (InputArray src, InputArray dst) - Calculates a perspective transform from four pairs of the corresponding points. void warpPerspective (InputArray src, OutputArray dst, InputArray M, Size dsize, int flags=INTER_LINEAR, int borderMode=BORDER_CONSTANT,…

• Rotate image 10 Jan 2014

  void warpAffine (InputArray src, OutputArray dst, InputArray M, Size dsize, int flags=INTER_LINEAR, int borderMode=BORDER_CONSTANT, const Scalar& borderValue=Scalar()) Parameters: src – input image. dst – output image that has the size dsize and the same type as src . M –…

• CAPTCHA formation in OpenCV 10 Jan 2014

  A CAPTCHA (an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart") is a type of challenge-response test used in computing to determine whether or not the user is human. It protects your website from spam by means of math logic, easily…

• Histogram Equalization 08 Jan 2014

  void equalizeHist (InputArray src, OutputArray dst) Parameters: src – Source 8-bit single channel image. dst – Destination image of the same size and type as src . Example: ---------- #include "opencv2/core/core.hpp" #include "opencv2/highgui/highgui.hpp" #include…

• Select a region on mouse click 07 Jan 2014

  The following program allows the user to select a point on the image and extracts the region around that point, from which it extracts information such as mean and variance of the locality. void setMouseCallback (const string& winname, MouseCallback onMouse, void* userdata=0 ) -…

• Detect Mouse Clicks and Moves on Image Window 07 Jan 2014

  void setMouseCallback (const string& winname, MouseCallback onMouse, void* userdata = 0) This function sets a callback function to be called every time any mouse events occurs in the specified window. Here is the detailed explanation of the each parameters of the above OpenCV…

• Resize image 07 Jan 2014

  void resize (InputArray src, OutputArray dst, Size dsize, double fx=0, double fy=0, int interpolation=INTER_LINEAR ) - The function resize resize s the image src down to or up to the specified size. Parameters: src – input image. dst – output image; it has the size dsize (when…

• Kalman Filter Implementation (Tracking mouse position) 04 Jan 2014

  KalmanFilter:: KalmanFilter (int dynamParams, int measureParams, int controlParams=0, int type=CV_32F) Parameters: dynamParams – Dimensionality of the state. measureParams – Dimensionality of the measurement. controlParams – Dimensionality of the control vector. type – Type of…

• Face detection using webcam 04 Jan 2014

  Example: ---------- #include "opencv2/objdetect/objdetect.hpp" #include "opencv2/highgui/highgui.hpp" #include "opencv2/imgproc/imgproc.hpp" #include using namespace cv; using namespace std; int main() { Mat image; CvCapture* capture; // Read the video stream capture =…

• Putting a mask on face using OpenCV 06 Nov 2013

  This is a example to put a mask on your face. This is a fun application that is meant to be used for entertainment purpose. You might have seen such apps in google hangouts. Steps: Detect face from the input video frame Load the mask and make the white region of the mask…

• Calculating time taken by the code 02 Nov 2013

  How to calculate the time of execution of the code??? Here is a small code to make use of "time.h" for tracking the time of execution. Example 1: ------------ #include ...***...***...***... clock_t start, end; double elapsed; start = clock(); /* Your code */ end = clock();…

• Faster face detection by varying detectMultiScale function parameters 01 Nov 2013

  In example 1, a simple face detection code is provided which runs at 1-2 frames per second. To make it faster, we can modify the parameters to detectMultiScale function to achieve very high frame rate. Example 2 provides the code for minor optimization of code to make it…

• Bitwise AND, OR, XOR and NOT 31 Oct 2013

  void bitwise_and (InputArray src1, InputArray src2, OutputArray dst, InputArray mask=noArray()) Calculates the per-element bit-wise conjunction of two arrays or an array and a scalar. Parameters: src1 – first input array or a scalar. src2 – second input array or a scalar. src –…

• Histogram Calculation 31 Oct 2013

  void calcHist (const Mat* images, int nimages, const int* channels, InputArray mask, OutputArray hist, int dims, const int* histSize, const float** ranges, bool uniform=true, bool accumulate=false ) Calculates a histogram of a set of arrays. Parameters: images – Source arrays.…

• Split and Merge functions 31 Oct 2013

  void split (InputArray m, OutputArrayOfArrays mv) Divides a multi-channel array into several single-channel arrays. Parameters: src – input multi-channel array. mv – output array or vector of arrays; in the first variant of the function the number of arrays must match…

• Convex Hull 27 Oct 2013

  X is a bounded subset of the plane, the convex hull may be visualized as the shape formed by a rubber band stretched around X . The convex hull of a set X of points in the Euclidean plane is the smallest convex set that contains X. when Formally, the convex hull may be defined…

Report this feed