Dark Effect on image in ImageView (Android)

Before Dark Effect

After Dark Effect

Create new Android Project

Project Name: PlayingwithBitmaps

Build Target: Android 2.3.3   //or greater than that

Application Name: PlayingwithBitmaps

Package Name: com.hamad.playingwithbitmaps

Create Activity: Main

Min SDK: 10 // or greater than that

1. create main layout:

• One image view to display the image.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000"
    android:id="@+id/rlMain" >

    <ImageView
        android:id="@+id/imViewAndroid"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:src="@drawable/car" />

</RelativeLayout>

 2. code of main activity:

package com.shaikhhamadali.blogspot.playingwithbitmaps;

import java.util.Random;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.widget.ImageView;

public class Main extends Activity {
    ImageView imViewAndroid;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imViewAndroid = (ImageView) findViewById(R.id.imViewAndroid);
        imViewAndroid.setImageBitmap(applyDarkFilter(BitmapFactory.decodeResource(getResources(), R.drawable.beautiful)));
 }
 public Bitmap applyDarkFilter(Bitmap source) {
     // get image source size
     int width = source.getWidth();
     int height = source.getHeight();
     int[] pixels = new int[width * height];
     // get pixel array from source
     source.getPixels(pixels, 0, width, 0, 0, width, height);
     // create random object
     Random random = new Random();
  
     int R, G, B, index = 0, thresHold = 0;
     // iteration through pixels
     for(int y = 0; y < height; ++y) {
         for(int x = 0; x < width; ++x) {
             // get current index in 2D-matrix
             index = y * width + x;
             // get RGB colors
             R = Color.red(pixels[index]);
             G = Color.green(pixels[index]);
             B = Color.blue(pixels[index]);
             // generate threshold
             thresHold = random.nextInt(255);
             if(R < thresHold && G < thresHold && B < thresHold) {
                 pixels[index] = Color.rgb(0,0,0);
             }
         }
     }
     // create output bitmap
     Bitmap bmOut = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
     bmOut.setPixels(pixels, 0, width, 0, 0, width, height);
     return bmOut;
 }
}

  3. note that:

• With the help of this,applyDarkFilter() method you can apply Dark Filter Effect on image on click,on action_down etc.
• Basically, the algorithm is to generate a threshold number (0-255), if all R,G,B values of a pixel are less than the threshold, then set the pixel to black.

  4. conclusion:

• Some deep information about Dark Filter effect .
• Know how to apply Dark Filter Effect on image bitmap from drawables.

  5. About the post:

• By Using the Approach of Randomizing Image pixel, another filter is created,named Dark/Black filter,or enhance the noise of darkness
• this could also used as ink dropping effect.
•  The code seems to explain itself due to comments, and is very easy to understand.
•  Don’t mind to write a comment whatever you like to ask, to know,to suggest or recommend.
•  Hope you enjoy it!

6. Source Code:

        you can download the source code here

Cheers,

Hamad Ali Shaikh