image processing from scratch

what is this?

This repository contains many interesting image processing algorithms that are written from scratch. Read these codes will allow you to have a comprehensive understanding of the principles of these algorithms.

Implementation All codes were wrote in python3.7 or c++ moudles you may need: python:

• numpy for matix calculation
• matplotlib for reading and showing images
• opencv2 for some image operations

c++:

• opencv2

Usage you can always run a python script just by python script.py

for c++, you need to compile first cd build cmake .. make

when it's done, you are ready to run the executable file by ./program_name parameters Just make sure you have the images in the right path, and you might wanna modify the code a bit to process another image. Have fun!

Contents

• canny edge detection It is an algorithm that extracts edges of an image.

• hough transform It is an algorithm that can theoratically detects shapes that you can write formulas for it.

• harris corner detection This algorithm detects corners.

• fast fourier transform 2-D fourier transform for images using fft.

• sift Scale-invariant feature transform, a well-known technique to extract feature points for image matching. Now added c++ version along with SURF and ORB.

• KNN Using balanced K-D tree to find k nearest neighbors of K-dimension points.

• PCA&SVD Do PCA and SVD using jacobi rotation.(which is accurate but slow)

• Ransac Stitch different images together after knowing the sift keypoint pairs.

• watershed watershed segmentation algorithm.

• meanshift meanshift segmentation algorithm.

• generalized hough transform template match of images, detects a given template in an query image. The vote space is implemented with a sparse vector to support big images.

• closed-form image matting a classic image matting algorithm proposed in A Closed-Form Solution to Natural Image Matting

• haze removal Using dark channel prior and fast guided filter proposed in Single Image Haze Removal Using Dark Channel Prior and Fast Guided Filter

• a lot to be continued...