Rotating or Resizing an Image in OpenCV

The page will show you how to do some common image transformations in OpenCV, such as rotating an image, cropping an image or resizing an image without changing its aspect ratio. Rotating an Image in OpenCV The function below will rotate an image using cvGetQuadrangleSubPix(),

Color Conversions

The RGB color format can represent any standard color or brightness using a combination of Red, Green and Blue components. For efficiency, this is typically stored as a 24-bit number using 8-bits for each color component (0 to 255) so that for example, White is

Color-based Blob Detection

Blob detection is a fast and simple method that can be used for many machine vision tasks, such as tracking a red ball, finding a blue marker or detecting a person’s skin (Skin Detection can be very useful with Face Detection and Face Recognition using


OpenCV is a great library for creating Computer Vision software using state-of-the-art techniques, and is freely available for Windows, Linux, Mac and even Android & iPhone. OpenCV was originally designed by Intel in 1999 to show how fast Intel CPUs can run. So most of

Introduction to Face Detection and Face Recognition

“Face Recognition” is a very active area in the Computer Vision and Biometrics fields, as it has been studied vigorously for 25 years and is finally producing applications in security, robotics, human-computer-interfaces, digital cameras, games and entertainment. “Face Recognition” generally involves two stages: Face Detection,

Motivation for hand-optimized Assembly code

There’s a popular saying that “in 90% of cases, a modern compiler writes faster code than a typical Assembly programmer would”. But anyone that has actually tested this theory knows how wrong this statement is! Hand-written Assembly code is ALWAYS faster and/or smaller than the equivalent