set Gamma of image in ImageView (Android)

Before Gamma Correction

After Gamma Correction

Gamma (red=0.5,green=0.5,yellow0.5)

Gamma (red=0.6,green=0.6,yellow0.6) 

Gamma (red=0.8,green=0.8,yellow0.8)

Gamma (red=1.0,green=1.0,yellow=1.0)

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

<?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.BlurMaskFilter;
import android.graphics.Color;
import android.graphics.PorterDuff;
import android.graphics.BlurMaskFilter.Blur;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.Menu;
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(setGamma(BitmapFactory.decodeResource(getResources(), R.drawable.android_droid),0.8,0.8,0.8));
 }

 public static Bitmap setGamma(Bitmap src, double red, double green, double blue) {
  // create output image
  Bitmap bmOut = Bitmap.createBitmap(src.getWidth(), src.getHeight(), src.getConfig());
  // get image size
  int width = src.getWidth();
  int height = src.getHeight();
  // color information
  int A, R, G, B;
  int pixel;
  // constant value curve
  final int    MAX_SIZE = 256;
  final double MAX_VALUE_DBL = 255.0;
  final int    MAX_VALUE_INT = 255;
  final double REVERSE = 1.0;

  // gamma arrays
  int[] gammaR = new int[MAX_SIZE];
  int[] gammaG = new int[MAX_SIZE];
  int[] gammaB = new int[MAX_SIZE];

  // setting values for every gamma channels
  for(int i = 0; i < MAX_SIZE; ++i) {
   gammaR[i] = (int)Math.min(MAX_VALUE_INT,
     (int)((MAX_VALUE_DBL * Math.pow(i / MAX_VALUE_DBL, REVERSE / red)) + 0.5));
   gammaG[i] = (int)Math.min(MAX_VALUE_INT,
     (int)((MAX_VALUE_DBL * Math.pow(i / MAX_VALUE_DBL, REVERSE / green)) + 0.5));
   gammaB[i] = (int)Math.min(MAX_VALUE_INT,
     (int)((MAX_VALUE_DBL * Math.pow(i / MAX_VALUE_DBL, REVERSE / blue)) + 0.5));
  }

  // apply gamma table
  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);
    // look up gamma
    R = gammaR[Color.red(pixel)];
    G = gammaG[Color.green(pixel)];
    B = gammaB[Color.blue(pixel)];
    // set new color to output bitmap
    bmOut.setPixel(x, y, Color.argb(A, R, G, B));
   }
  }

  // return final image
  return bmOut;
 }

}

There are various computations on Gamma correction, however, I just pick up and implement the simplest one as mentioned on wikipedia..

  3. note that:

• You might want to refer about gamma correction on Wikipedia.
• with the help of this,setGamma() method you can set the gamma of image on click,on action_down etc

  4. conclusion:

• some deep information about gamma.
• Know how to set gamma 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