Update README.md

Author: darusc

README.md

@@ -1,13 +1,36 @@
 <img src="imgs/Banner.png" width=100%></img>
 
-
 ## Table of Contents
 - [Introduction](#introduction)
+- [How to use](#how-to-use)
 - [How it works](#how-it-works)
-- [Getting Started](#getting-started)
+- [Build](#build)
 
 ## Introduction
 
+This project is an android app that solves sudoku, hence the name, recognized from images using Optical Character Recognition or entered manually.
+
+I've built this project the first time in early 2022 ( [v1](https://github.com/hypertensiune/Android-Sudoku-Solver-OCR/tree/v1) branch ) and this is a refresh, an update to the original project.
+
+What's new:
+- Better image processing and sudoku board recognition
+- Better text recognition
+- Code refactoring in Kotlin
+- Improved documentation
+
+## How to use
+
+Download or [build](#build) the app yourself.
+Use it like a camera app, press the shutter button when the sudoku it's detected and it will be solved. You can also edit it or input it manually if you want.
+
+It works on both puzzles on paper or on screen, the only requirement is there is enough light and that it's smooth.
+
+<p align="center">
+  <img src="imgs/scr1.jpeg" width=30%></img>
+  &nbsp;&nbsp&nbsp;&nbsp&nbsp;
+  <img src="imgs/scr2.jpeg" width=30%></img>
+</p>
+
 ## How it works
 
 ### Sudoku board detection
@@ -19,8 +42,6 @@ To identify the sudoku board the input image is processed as follows with [OpenC
 
 The numbers are detected using [MLKit Text Recognition](https://developers.google.com/ml-kit/vision/text-recognition/v2).
 
-<br>
-
 <p align="center">
   <img src="demo/demo1.gif"></img>
 </p>
@@ -29,11 +50,11 @@ The numbers are detected using [MLKit Text Recognition](https://developers.googl
 
 ### Solving
 For solving the puzzle I'm using a fairly simple, brute-force algorithm that relies on backtracking to generate the valid solution. 
-<br>
+
 It goes through the whole 2D array and for each number that needs to be found it tries all possibilities and continues with the following numbers. 
-<br> 
-<br>
-For each cell there are 9 possible numbers which means the time complexity of this algorithm is O(9<sup>N</sup>).
+
+
+For each cell there are 9 possible numbers which means the time complexity of this algorithm is O(9<sup>n</sup>).
 
 ```
 private fun solve(index: Int = 0): Boolean {
@@ -64,4 +85,48 @@ private fun solve(index: Int = 0): Boolean {
   <span>Solve algorithm demo</span>
 </p>
 
-## Getting Started
+## Build
+
+- Download or clone the repository and open it in Android Studio.
+- Download the android version of [OpenCV](https://opencv.org/releases/). I used the latest version, 4.8.0.
+- Import the OpenCV module in Android Studio.
+    * Click **File > New > Import Module**, select the **OpenCV-android-sdk/sdk** directory and change the module name to **opencv**.
+    * Goto **File > Project Structure > Dependencies** and on the **app** module add **opencv** as a dependency.
+    * In **opencv build.gradle** add  ```android { namespace 'org.opencv' }```, change ```compileSdkVersion``` and ```targetSdkVersion``` to 33 and finally, add
+      ```
+      kotlinOptions {
+        jvmTarget = '1.8'
+      }
+      buildFeatures {
+        buildConfig true
+        aidl true
+      }
+      ```
+    * Further we need to modify the following classes in the OpenCV module:
+        * **CameraBridgeViewBase**: add ```canvas.rotate(90f, canvas.getWidth() / 2, canvas.getHeight() / 2);``` in function ```deliverAndDrawFrame```, right before drawing the bitmap.
+        * **JavaCameraView** add:
+            ```
+            public void turnOnFlashlight(){
+                Camera.Parameters params = mCamera.getParameters();
+                params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
+                mCamera.setParameters(params);
+            }
+                
+            public void turnOffFlashLight(){
+                Camera.Parameters params = mCamera.getParameters();
+                params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
+                mCamera.setParameters(params);
+            }
+            ```
+            In function ```iniliazeCamera``` change
+            ```
+            if ((getLayoutParams().width == LayoutParams.MATCH_PARENT) && (getLayoutParams().height == LayoutParams.MATCH_PARENT))
+                mScale = Math.min(((float)height)/mFrameHeight, ((float)width)/mFrameWidth);
+            else
+                mScale = 0;
+            ```
+            to
+            ```
+            mScale = Math.max(((float)height)/mFrameHeight, ((float)width)/mFrameWidth);
+            ```
+- Done, you can now build the project