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Sandipan Dey's Blog (42)

Solving Some Image Processing Problems with Python libraries - Part 3

In this article a few more popular image processing problems along with their solutions are going to be discussed. Python image processing libraries are going to be used to solve these problems.

Histogram Matching with color images

As described here, here is the algorithm:

  1. The cumulative histogram is computed for each image dataset, see the figure below.
  2. For any…
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Added by Sandipan Dey on August 16, 2018 at 1:30pm — No Comments

Solving Some Image Processing Problems with Python libraries - Part 2

In this article a few more popular image processing problems along with their solutions are going to be discussed. Python image processing libraries are going to be used to solve these problems.

Some Applications of DFT 

0. Fourier Transform of a Gaussian Kernel is another Gaussian Kernel

Also, the spread in the frequency domain  inversely proportional to the spread in the spatial domain. Here is the proof:…

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Added by Sandipan Dey on August 16, 2018 at 1:00pm — No Comments

Solving Some Image Processing Problems with Python libraries - Part 1

In this article a few popular image processing problems along with their solutions are going to be discussed. Python image processing libraries are going to be used to solve these problems.

 

Image Transformations and Warping

 

0. Display RGB image color channels in 3D

  1. A gray-scale image can be thought of a 2-D function f(x,y) of the pixel…
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Added by Sandipan Dey on August 16, 2018 at 1:00pm — No Comments

Few Machine Learning Problems (with Python implementation)

1. Back-propagation

This problem also appeared as an assignment problem in the coursera online course Mathematics for Machine Learning: Multivariate Calculus. The description of the problem is taken from the assignment itself.

In this assignment, we shall train a neural network to draw a curve. The curve takes one input variable, the…

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Added by Sandipan Dey on May 31, 2018 at 10:00pm — No Comments

Implementing PEGASOS: Primal Estimated sub-GrAdient SOlver for SVM, Logistic Regression and Application in Sentiment Classification (in Python)

Although a support vector machine model (binary classifier) is more commonly built by solving a quadratic programming problem in the dual space,  it can be built fast by solving the primal optimization problem also. In this article a Support Vector Machine implementation is going to be described by solving the primal optimization…

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Added by Sandipan Dey on April 28, 2018 at 3:30pm — No Comments

Implementing a Soft-Margin Kernelized Support Vector Machine Binary Classifier with Quadratic Programming in R and Python

In this article, couple of implementations of the support vector machine binary classifier with quadratic programming libraries (in R and python respectively) and application on a few datasets are going to be discussed.  

The next figure describes the basics of Soft-Margin SVM (without kernels).

svm_slack.png SVM in a nutshell

  • Given a (training) dataset consisting of positive and negative class instances.
  • Objective is to find…
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Added by Sandipan Dey on April 23, 2018 at 9:30am — No Comments

Some Reinforcement Learning: The Greedy and Explore-Exploit Algorithms for the Multi-Armed Bandit Framework in Python

In this article the multi-armed bandit framework problem and a few algorithms to solve the problem is going to be discussed. This problem appeared as a lab assignment in the edX course DAT257x: Reinforcement Learning Explained by Microsoft. The problem description is taken from the assignment itself.

The Problem Statement and Some Theory

Given a set of  actions with some unknown reward distributions, …

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Added by Sandipan Dey on April 4, 2018 at 9:30am — No Comments

Learning Distributed Word Representations with Neural Network: an implementation from scratch in Octave

In this article, the problem of learning word representations with neural network from scratch is going to be described. This problem appeared as an assignment in the Coursera course Neural Networks for Machine Learning, taught by  Prof.  Geoffrey Hinton from the University of Toronto in 2012.  

 

Problem Statement

In this article…

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Added by Sandipan Dey on March 18, 2018 at 12:00am — No Comments

Autonomous Driving – Car detection with YOLO Model with Keras in Python

In this article, object detection using the very powerful YOLO model will be described, particularly in the context of car detection for autonomous driving. This problem appeared as an assignment in the coursera course Convolution Networks which is a part of the Deep Learning Specialization (taught by Prof. Andrew Ng.,  from Stanford…

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Added by Sandipan Dey on March 11, 2018 at 11:30pm — 3 Comments

Implementing Lucas-Kanade Optical Flow algorithm in Python

In this article an implementation of the Lucas-Kanade optical flow algorithm is going to be described. This problem appeared as an assignment in  a computer vision course from UCSD. The inputs will be sequences of images (subsequent frames from a video) and the algorithm will output an optical flow field (u, v) and trace the motion of the moving objects. The problem description is taken from the assignment itself.

 


Problem…

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Added by Sandipan Dey on February 28, 2018 at 11:30am — No Comments

Graph-Based Image Segmentation in Python

In this article, an implementation of an efficient graph-based image segmentation technique will be described, this algorithm was proposed by Felzenszwalb et. al. from MIT.  The slides on this paper can be found from Stanford Vision Lab.. The algorithm is closely related…

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Added by Sandipan Dey on February 28, 2018 at 11:30am — No Comments

Image Colorization Using Optimization in Python

This article is inspired by this SIGGRAPH paper by Levin et. al, for which they took this patent , the paper was referred to in the course CS1114 from Cornell.  This method is also discussed in the coursera online image processing course by NorthWestern University. Some part of the problem description is taken from the paper itself. Also, one can refer to the implementation provided by the authors in matlab, the following …

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Added by Sandipan Dey on February 13, 2018 at 1:00pm — No Comments

Interactive Image Segmentation with Graph-Cut in Python

In this article, interactive image segmentation with graph-cut is going to be discussed. and it will be used to segment the source object from the background in an image. This segmentation technique was proposed by Boycov and Jolli in this paper

Problem Statement: Interactive graph-cut segmentation

Let’s implement…

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Added by Sandipan Dey on February 13, 2018 at 10:30am — No Comments

Recursive Graphics, Bi/Tri-linear Interpolation, Anti-aliasing and Image Transformation in Python

The following problem appeared in an assignment in the Princeton course COS 126 . The problem description is taken from the course itself.

Recursive Graphics

Write a program that plots a Sierpinski triangle, as illustrated below. Then develop a program that plots a recursive patterns of your own design.…

sierpinski9.png

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Added by Sandipan Dey on January 24, 2018 at 10:00am — No Comments

Some Applications of Markov Chain in Python

In this article a few simple applications of Markov chain are going to be discussed as a solution to a few text processing problems. These problems appeared as assignments in a few courses, the descriptions are taken straightaway from the courses themselves.

1. Markov Model of Natural…

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Added by Sandipan Dey on January 16, 2018 at 8:30pm — No Comments

Deep Learning & Art: Neural Style Transfer – An Implementation with Tensorflow in Python

This problem appeared as an assignment in the online coursera course Convolution Neural Networks by Prof Andrew Ng, (deeplearing.ai).  The description of the problem is taken straightway from the assignment.

In this assignment, we shall:

  • Implement the neural style transfer algorithm
  • Generate novel artistic images using our algorithm

Most of the…

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Added by Sandipan Dey on January 2, 2018 at 1:00pm — 2 Comments

Data Science with Python: Exploratory Analysis with Movie-Ratings and Fraud Detection with Credit-Card Transactions

The following problems are taken from the projects / assignments in the edX course Python for Data Science and the coursera course Applied Machine Learning in Python (UMich).

 

1. Exploratory Analysis to Find Trends in Average Movie Ratings for different Genres

Dataset

● The IMDB Movie Dataset (MovieLens 20M) is used for the analysis.

● The dataset is downloaded from …

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Added by Sandipan Dey on December 16, 2017 at 1:30pm — 5 Comments

Some Deep Learning with Python, TensorFlow and Keras

he following problems are taken from a few assignments from the coursera courses Introduction to Deep Learning (by Higher School of Economics) and Neural Networks and Deep Learning (by Prof Andrew Ng, deeplearning.ai). The problem descriptions are taken straightaway from the assignments.

 

1. Linear models, Optimization…

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Added by Sandipan Dey on November 25, 2017 at 2:00pm — 4 Comments

Some Computational Photography: Image Quilting (Texture Synthesis) with Dynamic Programming and Texture Transfer in Python

The following problems appeared as a programming assignment in the Computation Photography course (CS445) at UIUC. The description of the problem is taken from the assignment itself. In this assignment, a python implementation of the problems will be described instead of matlab, as expected in the course.

 

The Problems

  • The goal of this assignment is to implement the image quilting algorithm for

    texture synthesis and transfer,…
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Added by Sandipan Dey on October 24, 2017 at 1:30pm — No Comments

Seam Carving: Using Dynamic Programming to implement Context-Aware Image Resizing in Python

The following problem appeared as an assignment in the Algorithm Course (COS 226) at Princeton University taught by Prof. Sedgewick.  The following description of the problem is taken from the assignment itself.

The Seam Carving Problem

  • Seam-carving is a content-aware image resizing technique where the image…
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Added by Sandipan Dey on October 14, 2017 at 2:30pm — No Comments

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