Skip to main content

Posts

Showing posts from September, 2017

Face Detection using OpenCV and Python.

  Introduction Face detection is a computer technology that determines the locations and sizes of human faces in arbitrary (digital) images. It detects facial features and ignores anything else, such as buildings, trees and bodies. Face detection can be regarded as a more general case of face localization.  The first step in automatic facial recognition is the accurate detection of human faces in an arbitrary scene. When faces are localized exactly, the recognition is performed on the detected face. Haar Cascade Detection  It is a machine learning approach where a cascade function is trained from a lot of positive and negative images. This method was proposed by Paul Viola and Michael Jones in their Paper "Rapid Object Detection using a Boosted Cascade of Simple Features" in 2001. Initially, the algorithm needs a lot of positive (Images of Faces) and negative Images (images without faces) to train the classifier. Then we need to extract Haar features...

Popular Posts

Transparent Image overlay(Alpha blending) with OpenCV and Python

(a)Final Blended Image                     (b) Background Image                             (c)Foreground Image                               Alpha blending Alpha blending is the process of overlaying a foreground image with transparency over a background Image. The transparent image is generally a PNG image.It consists of four channels (RGBA).The fourth channel is the alpha channel which holds the transparency magnitude. Image (b) is a background image and image (c) is the foreground / overlay image. Image (a) is the final blended image obtained by blending  the overalay image using the alpha mask.  Below is the image(Fig d) of the alpha channel of the overlay  image. (d).Alpha Channel At every pixel of the image, we blend the background...

Fast Pixel Processing with OpenCV and Python

In this post. I will explain how fast pixel manipulation of an image can be done in Python and OpenCV. Image processing is a CPU intensive task. It involves processing on large arrays. Hence when you are implementing your Image Processing algorithm, you algorithm needs to be highly efficient. The type of operation that can be applied on an Image can be classified into three categories.