Computer Vision

Finding Affine Transform with Linear Least Squares

linear least squares is a method of fitting a model to data in which the relation between data and unknown paramere can be expressed in a linear form. \( Ax=b\) \( X^{*}= \underset{x}{\mathrm{argmin}}= \|Ax-b\|^{2} =(A^{T}A)^{-1}A^{T}b \)

And testing the code:

 

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Peak Signal-to-Noise Ratio (PSNR) in Image using OpenCV and Matlab

Peak signal-to-noise ratio (PSNR) shows the ratio between the maximum possible power of a signal and the power of the same image with noise. PSNR is usually expressed in logarithmic decibel scale. \( MSE =1/m*n \sum_{i=0}^{m-1} \sum_{j=0}^{n-1}  [   Image( i,j)  -NoisyImage( i,j)  ]  ^2   \) \( PSNR =10* \log_{10} \Bigg(MAXI^2/MSE\Bigg)  \) MSE is Mean Square Error and MAXI is

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Seam Carving Algorithm for Content-Aware Image Resizing with Matlab Code

Seam carving is an algorithm for resizing images while keeping the most prominent and conspicuous pixels in the image. The important pixels in an image are usually those who are located over horizontal or vertical edges, so to throw away some pixels we first find horizontal and vertical edges and store their magnitude as pixel

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HARRIS Corner detector explained

 

HARRIS Corner detector explained Read More »

Eigenvectors of PCL pointcloud (moment of inertia)

The snippet below shows how to computer PCA eigenvectors and eigenvalues (in this case could be interpreted as the moment of inertia).

 

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A GUI ROS-package for cropping pcl pointcloud with dynamic reconfigure

This ROS package enables you to crop the scene from Kinect (input topic type: PCL pointcloud). You can even enable fitting a plane to remove the ground from the scene and by adjusting correct parameter you can get the desired object from the scene. code available on my Github.

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List of OpenCv matrix types and mapping numbers

ref: Special thanks to this post.

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Multi scale face detector using HOG features and support vector machine

In this part, I trained an SVM over images of  “face” or “not face” (36 × 36 pixels), using HOG features. I used VLFeat library for both HOG and the SVM. Example of face images: Example of nonface images: I divided the dataset into a training and a test set (80% and 20% respectively) and computed the HOG

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2D pose estimation of human body using CNS and PCA

This work is the second part of my master thesis (part I). In this part, I developed an algorithm for 2D pose estimation of the human body. To do this, I created a software with QT that could generate 2D contours representing human body. Then I send these contours for evaluation to CNS(Contrast Normalized Sobel) [1]

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Human detection on mobile camera using HOG and tracking them using Kalman filter

This is the part I of the work that I did for my master thesis (part II). In this work first, I computed HOG (Histogram of oriented gradients) on my images and then sent the computed histogram to a linear SVM (support vector machine). The SVM was trained with human and non-human images. The output of the classifier was

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