OpenCV Morphological Operations

In this tutorial, you will learn about applying morphological operations with OpenCV.

The morphological operations we’ll be covering include:

• Erosion
• Dilation
• Opening
• Closing
• Morphological gradient
• Black hat
• Top hat (also called “White hat”)

These image processing operations are applied to grayscale or binary images and are used for preprocessing for OCR algorithms, detecting barcodes, detecting license plates, and more.

And sometimes a clever use of morphological operations can allow you to avoid more complicated (and computationally expensive) machine learning and deep learning algorithms.

As a serious computer vision practitioner, you need to understand morphological operations.

To learn how to apply morphological operations with OpenCV, just keep reading.

#opencv #python #data-science

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Ternary operator in Python?

1. Ternary Operator in Python

What is a ternary operator: The ternary operator is a conditional expression that means this is a comparison operator and results come on a true or false condition and it is the shortest way to writing an if-else statement. It is a condition in a single line replacing the multiline if-else code.

syntax : condition ? value_if_true : value_if_false

condition: A boolean expression evaluates true or false

value_if_true: a value to be assigned if the expression is evaluated to true.

value_if_false: A value to be assigned if the expression is evaluated to false.

How to use ternary operator in python here are some examples of Python ternary operator if-else.

Brief description of examples we have to take two variables a and b. The value of a is 10 and b is 20. find the minimum number using a ternary operator with one line of code. ( **min = a if a < b else b ) **. if a less than b then print a otherwise print b and second examples are the same as first and the third example is check number is even or odd.

#python #python ternary operator #ternary operator #ternary operator in if-else #ternary operator in python #ternary operator with dict #ternary operator with lambda

Unformatted input/output operations In C++

In this article, we will discuss the unformatted Input/Output operations In C++. Using objects cin and cout for the input and the output of data of various types is possible because of overloading of operator >> and << to recognize all the basic C++ types. The operator >> is overloaded in the istream class and operator << is overloaded in the ostream class.

The general format for reading data from the keyboard:

cin >> var1 >> var2 >> …. >> var_n;

• Here, var1, var2, ……, varn are the variable names that are declared already.
• The input data must be separated by white space characters and the data type of user input must be similar to the data types of the variables which are declared in the program.
• The operator >> reads the data character by character and assigns it to the indicated location.
• Reading of variables terminates when white space occurs or character type occurs that does not match the destination type.

#c++ #c++ programs #c++-operator overloading #cpp-input-output #cpp-operator #cpp-operator-overloading #operators

Create a Virtual Pen and Eraser with Python OpenCV - Genial Code

Learn Free how to create a virtual pen and eraser with python and OpenCV with source code and complete guide. This entire application is built fundamentally on contour detection. It can be thought of as something like closed color curves on compromises that have the same color or intensity, it’s like a blob. In this project we use color masking to get the binary mask of our target color pen, then we use the counter detection to find the location of this pen and the contour to find it.

#python #create virtual pen and eraser with opencv #create virtual pen and eraser with python opencv #programming #opencv #python opencv

A Simple HDR Implementation on OpenCV Python

Learn how to create a high dynamic range (HDR) image using Python and OpenCV

HDR images encompass the information of multiple pictures with different exposures. In a scene which the source of light is uneven, a single shot may overexpose certain areas of the image and details will be lost due to elevated brightness. Conversely, this picture may also present underexposed areas which will also lead to information loss.

To create an HDR image you will need:

1. Take pictures with different exposures. Minimum of 2, generally 3, you can use more than 3 images but it will take a lot of CPU resources.
2. Align the images. Even if you use a tripod you will need to perform this step (we are talking about pixel level alignment). Not properly aligning your image will lead to artifacts and ‘ghosts’ in your HDR image.
3. Merge the aligned images into one.
4. Perform tone mapping on the merged image. In nature the minimum possible brightness is zero but the maximum is not limited to 255, in fact there is no limit to it, it can be infinity. For this reason we need to map the image obtained in the third step to a (0, 255) range. This can be achieved with tone mapping.

#hdr #opencv #computer-vision #python #opencv #opencv python

OpenCV + CUDA + AWS EC2 + (No More Tears)

By default, there is no need to enable OpenCV with CUDA for GPU processing, but during production, when you have heavy OpenCV manipulations to do on image/video files, we can make use of the OpenCV CUDA library to make those operations to run on GPU rather than CPU and it saves a lot of time.

It was not easy as it is said to connect the OpenCV library to enable it with CUDA, I had to go through a painful process for a week to establish the connection properly, also its both time & money consuming process. So this time I want to record the overall process for my future, as well as for others.

For the demonstration, I am renting an EC2 instance with a p3.8xlarge instance in the AWS, which has 4 Nvidia GPUs.

Source — AWS EC2 Pricing

So if you need any help in starting an EC2 instance for the first time, you can refer to my previous post on Step by Step Creation of an EC2 Instance in AWS and Access it via Putty & WinSCP and during the process select the GPU instance you require.

Now after ssh-ing into the instance, before we get into the process we need to install a lot of packages to make the environment ready.

_Note: I have consolidated all the commands I ran from start to end and added them at the bottom. If you are more curious find them here in this __link _and follow along.

Run the below commands one after another on your instance and also I have attested the screenshots to compare the outputs against mine.

All the screenshots used hereafter are sourced by the author.

Table of Contents:

1. Install OpenCV Dependencies, Nvidia CUDA driver, CUDA toolkit
2. Download OpenCV Source Code
3. Configure Python Virtual Environment
4. Determine Your CUDA Architecture Version
5. Configure OpenCV with Nvidia GPU Support
6. Compile OpenCV and Create a Symbolic link
7. References
8. History of Commands

Step 1: Install OpenCV Dependencies, Nvidia CUDA driver, CUDA toolkit.

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install build-essential cmake unzip pkg-config
sudo apt-get install gcc-6 g++-6
sudo apt-get install screen
sudo apt-get install libxmu-dev libxi-dev libglu1-mesa libglu1-mesa-dev
sudo apt-get install libjpeg-dev libpng-dev libtiff-dev
sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libv4l-dev
sudo apt-get install libxvidcore-dev libx264-dev
sudo apt-get install libopenblas-dev libatlas-base-dev liblapack-dev gfortran
sudo apt-get install libhdf5-serial-dev
sudo apt-get install python3-dev python3-tk python-imaging-tk
sudo apt-get install libgtk-3-dev
sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt-get update
sudo apt-get install nvidia-driver-418
sudo reboot

#opencv-in-ubuntu #opencv-python #cuda #nvidia #opencv #ubuntu