Archive | Image Descriptors

OpenCV panorama stitching

In today’s blog post, I’ll demonstrate how to perform image stitching and panorama construction using Python and OpenCV. Given two images, we’ll “stitch” them together to create a simple panorama, as seen in the example above. To construct our image panorama, we’ll utilize computer vision and image processing techniques such as: keypoint detection and local invariant […]

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HOG detectMultiScale parameters explained

Last week we discussed how to use OpenCV and Python to perform pedestrian detection. To accomplish this, we leveraged the built-in HOG + Linear SVM detector that OpenCV ships with, allowing us to detect people in images. However, one aspect of the HOG person detector we did not discuss in detail is the detectMultiScale  function; specifically, […]

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Implementing RootSIFT in Python and OpenCV

Still using the original, plain ole’ implementation of SIFT by David Lowe? Well, according to Arandjelovic and Zisserman in their 2012 paper, Three things everyone should know to improve object retrieval, you’re selling yourself (and your accuracy) short by using the original implementation. Instead, you should be utilizing a simple extension to SIFT, called RootSIFT, that can […]

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How-To: 3 Ways to Compare Histograms using OpenCV and Python

So you’ve extracted color histograms from a set of images… But how are you going to compare them for similarity? You’ll need a distance function to handle that. But which one? How you choose? And how do you compare histograms using Python and OpenCV? Don’t worry, I’ve got you covered. In this blog post I’ll […]

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Charizard Explains How To Describe and Quantify an Image Using Feature Vectors

If you haven’t noticed, the term “feature vector” is used quite often in this blog. And while we’ve seen it a lot, I wanted to dedicate an entire post to defining what exactly a feature vector is. What is an Image Feature Vector? Image Feature Vector: An abstraction of an image used to characterize and […]

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