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...