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,
you can download the source code here
Hamad Ali Shaikh