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Evaluation Metrics for Machine Learning Model

Evaluation metrics play an important role in achieving the optimal model during model training. It is a way to quantify the performance of the Machine learning Model. For simplicity, I'll be focusing on binary classification. But all the below metrics can be extended for multi-class classification. Let us first understand the basic building block of metrics used to evaluate a classification model. Suppose we have trained a binary image classifier model that predicts whether there is a cat or not in the image. Positive Class: Cat is a Positive class . Negative Class: No Cat is the Negative class, It can be anything(dog, horse, background, etc.) except cat in the image. Fig. 1 Fig. 2 True Positive (TP): It is an outcome when the model correctly predicts the positive class. i.e the actual image is "Cat" and the model also predicts "Cat" . False Positive (FP):   It is an outcome when the model incorrectly predicts the positive class. i.e the a...

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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.