Reducing color depth of image in ImageView (Android)

Before reducind color depth

After reducind color depth

64bit

128bit

 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/beautiful" />

</RelativeLayout>

 2. code of main activity:

package com.shaikhhamadali.blogspot.playingwithbitmaps;

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(reduceColorDepth(BitmapFactory.decodeResource(getResources(), R.drawable.android_droid),16));
 }

 public Bitmap reduceColorDepth(Bitmap src, int bitOffset) {
  // get image original size
  int width = src.getWidth();
  int height = src.getHeight();
  // create output bitmap
  Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig());
  // color information
  int A, R, G, B;
  int pixel;

  // scan through all pixels
  for(int x = 0; x < width; ++x) {
   for(int y = 0; y < height; ++y) {
    // get pixel color
    pixel = src.getPixel(x, y);
    A = Color.alpha(pixel);
    R = Color.red(pixel);
    G = Color.green(pixel);
    B = Color.blue(pixel);

    // round-off color offset
    R = ((R + (bitOffset / 2)) - ((R + (bitOffset / 2)) % bitOffset) - 1);
    if(R < 0) { R = 0; }
    G = ((G + (bitOffset / 2)) - ((G + (bitOffset / 2)) % bitOffset) - 1);
    if(G < 0) { G = 0; }
    B = ((B + (bitOffset / 2)) - ((B + (bitOffset / 2)) % bitOffset) - 1);
    if(B < 0) { B = 0; }

    // set pixel color to output bitmap
    bmOut.setPixel(x, y, Color.argb(A, R, G, B));
   }
  }

  // return final image
  return bmOut;
 }

}

Reducing color depth involves converting to standard values.

For example: if I want to offset 32, then each image color channel will apply the range: 0, 31, 63 .

  3. note that:

• You might want to refer about list of monochrome on Wikipedia,color depth on Wikipedia,
• with the help of this,reduceColorDepth() method you can set the color depth of image on click,on action_down etc

  4. conclusion:

• some deep information about color depth.
• Know how to set color depth of an image bitmap from drawables.

  5. About the post:

• 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