Convert ImageView to black and white, and set brightness, using ColorFilter

MainActivity.java

package com.blogspot.android_er.androidcolorfilter;

import android.graphics.ColorFilter;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.PorterDuff;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    ImageView imageView;
    SeekBar brightnessBar;
    TextView brightnessInfo;

    PorterDuff.Mode[] optMode = PorterDuff.Mode.values();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = (ImageView)findViewById(R.id.iv);
        brightnessBar = (SeekBar)findViewById(R.id.bar_brightness);
        brightnessInfo = (TextView)findViewById(R.id.brightness_info);

        brightnessBar.setOnSeekBarChangeListener(brightnessBarChangeListener);

        setBlackAndWhite(imageView);
    }

    SeekBar.OnSeekBarChangeListener brightnessBarChangeListener
            = new SeekBar.OnSeekBarChangeListener(){

        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            setBlackAndWhite(imageView);
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {

        }

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {

        }
    };

    private void setBlackAndWhite(ImageView iv){

        float brightness = (float)(brightnessBar.getProgress() - 255);

        float[] colorMatrix = {
                0.33f, 0.33f, 0.33f, 0, brightness, //red
                0.33f, 0.33f, 0.33f, 0, brightness, //green
                0.33f, 0.33f, 0.33f, 0, brightness, //blue
                0, 0, 0, 1, 0    //alpha
        };

        ColorFilter colorFilter = new ColorMatrixColorFilter(colorMatrix);
        iv.setColorFilter(colorFilter);

        brightnessInfo.setText(String.valueOf(brightness));
    }

}

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <ImageView
        android:id="@+id/iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/ic_launcher"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Brightness"/>

    <SeekBar
        android:id="@+id/bar_brightness"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="512"
        android:progress="255"/>

    <TextView
        android:id="@+id/brightness_info"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Brightness"/>
</LinearLayout>

Related:
- Android example code using ColorFilter