May 18, 2012

Android image processing - Edge Detect

Read it first: Image processing on Android, the basic logic of Convolution Matrix. 

It's example to perform edge enhance on Android.

Edge Detect


package com.AndroidImageProcessing;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;

public class AndroidImageProcessingActivity extends Activity {
 
 final static int KERNAL_WIDTH = 3;
 final static int KERNAL_HEIGHT = 3;
 
 int[][] kernal ={
   {0, -1, 0},
   {-1, 4, -1},
   {0, -1, 0}
 };
 
 ImageView imageSource, imageAfter;
 Bitmap bitmap_Source;
 ProgressBar progressBar;
 
 private Handler handler;
 Bitmap afterProcess;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        imageSource = (ImageView)findViewById(R.id.imageSource);
        imageAfter = (ImageView)findViewById(R.id.imageAfter);
        progressBar = (ProgressBar)findViewById(R.id.progressBar);
        
        bitmap_Source = BitmapFactory.decodeResource(getResources(), R.drawable.testpicture);

        handler = new Handler();
        StratBackgroundProcess();
    }
    
    private void StratBackgroundProcess(){
     
     Runnable runnable = new Runnable(){

   @Override
   public void run() {
    afterProcess = processingBitmap(bitmap_Source, kernal);
    
    handler.post(new Runnable(){

     @Override
     public void run() {
      progressBar.setVisibility(View.GONE);
      imageAfter.setImageBitmap(afterProcess);
     }
     
    });
   }
     };
     new Thread(runnable).start();
    }
    
    private Bitmap processingBitmap(Bitmap src, int[][] knl){
     Bitmap dest = Bitmap.createBitmap(
       src.getWidth(), src.getHeight(), src.getConfig());
     
     int bmWidth = src.getWidth();
     int bmHeight = src.getHeight();
     int bmWidth_MINUS_2 = bmWidth - 2;
     int bmHeight_MINUS_2 = bmHeight - 2;
     
     for(int i = 1; i <= bmWidth_MINUS_2; i++){
      for(int j = 1; j <= bmHeight_MINUS_2; j++){
       
       //get the surround 3*3 pixel of current src[i][j] into a matrix subSrc[][]
       int[][] subSrc = new int[KERNAL_WIDTH][KERNAL_HEIGHT];
       for(int k = 0; k < KERNAL_WIDTH; k++){
        for(int l = 0; l < KERNAL_HEIGHT; l++){
         subSrc[k][l] = src.getPixel(i-1+k, j-1+l);
        }
       }
       
       //subSum = subSrc[][] * knl[][]
       int subSumA = 0;
       int subSumR = 0;
       int subSumG = 0;
       int subSumB = 0;

       for(int k = 0; k < KERNAL_WIDTH; k++){
        for(int l = 0; l < KERNAL_HEIGHT; l++){
         subSumR += Color.red(subSrc[k][l]) * knl[k][l];
         subSumG += Color.green(subSrc[k][l]) * knl[k][l];
         subSumB += Color.blue(subSrc[k][l]) * knl[k][l];
        }
       }

       subSumA = Color.alpha(src.getPixel(i, j));

       if(subSumR <0){
        subSumR = 0;
       }else if(subSumR > 255){
        subSumR = 255; 
       }
       
       if(subSumG <0){
        subSumG = 0;
       }else if(subSumG > 255){
        subSumG = 255;
       }
       
       if(subSumB <0){
        subSumB = 0;
       }else if(subSumB > 255){
        subSumB = 255;
       }

       dest.setPixel(i, j, Color.argb(
         subSumA, 
         subSumR, 
         subSumG, 
         subSumB));
      } 
     }
     
     return dest;
    }

}


main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <ScrollView 
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <LinearLayout 
            android:layout_width="fill_parent"
         android:layout_height="fill_parent"
         android:orientation="vertical" >
         <TextView
             android:layout_width="fill_parent"
             android:layout_height="wrap_content"
             android:text="Original" />
      <ImageView
          android:id="@+id/imageSource" 
          android:layout_width="wrap_content"
          android:layout_height="wrap_content" 
          android:src="@drawable/testpicture"/>
      <TextView
             android:layout_width="fill_parent"
             android:layout_height="wrap_content"
             android:text="Result" />
      <FrameLayout 
          android:layout_width="wrap_content"
          android:layout_height="wrap_content">
          <ImageView
              android:id="@+id/imageAfter" 
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"/>
          <ProgressBar
              android:id="@+id/progressBar"
              style="?android:attr/progressBarStyleLarge"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"/>
      </FrameLayout>
      
     </LinearLayout>
    </ScrollView>

</LinearLayout>



4 comments:

  1. Hello,
    Nice....but your program not run in my simulation.
    How size your image (test picture) in drawable? Thanks

    ReplyDelete
  2. Hi..
    Thx for your code, but why the program not return anything? Thanks

    ReplyDelete
  3. Very good and perfect example.
    Please tell me how to bold the result?

    ReplyDelete
  4. it is running perfect but it's too slow...

    ReplyDelete

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