This document summarizes a final project to implement the PatchMatch algorithm for finding approximate nearest neighbor matches between image patches on an Android device. It introduces PatchMatch as a randomized correspondence algorithm that can be used for image editing tasks like retargeting, hole filling, and cloning. It then describes porting the core PatchMatch C/C++ library to Android using the Java Native Interface and Android Native Development Kit to build a PatchMatch library for Android.

1. VFX FINAL PROJECT:
PATCHDROID - PATCHMATCH
LIBRARY ON ANDROID DEVICE
電子所
R01943028 歐順興
D01943013 張嘉洋

2. A new randomized algorithm for quickly finding approximate
nearest-neighbor matches between image patches.
INTRODUCTION – PATCHMATCH
Finding similar patch Reconstruct by patches
Ref. Connelly Barnes, Eli Shechtman, Adam Finkelstein, Dan B Goldman, “PatchMatch: A Randomized Correspondence Algorithm for Structural Image Editing” ACM Transactions on Graphics (Proc. SIGGRAPH), August 2009

3. ----- PatchMatch: Ns x Ms x w2 x iteration
ALGORITHM
• How to find out all nearest patches for each pixel in source image?
• Patch size : w x w , source image : Ns x Ms , target image: Nt x Mt
• Brute force: Ns x Ms x Nt x Mt x w2
Finding similar patch Random Initial Guess
Propagation
= argmin ( , , )
Random search
= argmin ( + wαR )
¼ iteration 5 iteration

4. APPLICATION
• Retargeting
ResizeMaintain
Ratio

5. APPLICATION
• Retargeting – gradual resizing
x [0.9 1]
iterativelyx [0.9 1]
Final Result

6. DEMO

7. PATCHMATCH LIBRARY FOR
ANDROID
• Core algorithm in C/C++ code.
• Wrapped with Java-Native-Interface (JNI)
• Compiled with Android Native Development Kit (NDK)

8. •

9. APPLICATION
• Hole filling(inpainting)
Original ConstraintResult
iteratively

10. APPLICATION
• Cloning
Original Hard CopyResult
iteratively