Changing an ImageView to black and white

Question

I would like to change an ImageView's image to black and white. The only thing is my code allows the user to take a photo, that photo is placed in the imageview. I would like that photo to be black and white. If anyone knows how I could do this, I would appreciate it.

MainActivity:

package com.example.triptych4;  import java.io.File;  import android.app.Activity; import android.content.ContentResolver; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.provider.MediaStore; import android.util.Log; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.Gallery; import android.widget.ImageButton; import android.widget.ImageView; import android.widget.Toast;  public class MainActivity extends Activity {       // label our logs "CameraApp3"     private static String logtag = "CameraApp3";     // tells us which camera to take a picture from     private static int TAKE_PICTURE = 1;     // empty variable to hold our image Uri once we store it     private Uri imageUri;      private Integer[] pics = { R.drawable.android, R.drawable.android3d,           R.drawable.background3 };      private ImageView imageView;       @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          Gallery gallery = (Gallery) findViewById(R.id.gallery1);         gallery.setAdapter(new ImageAdapter(this));         imageView = (ImageView) findViewById(R.id.imageView1);          gallery.setOnItemClickListener( new AdapterView.OnItemClickListener() {             @Override             public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,                      long arg3) {                 Toast.makeText(getApplicationContext(), "pic:" + arg2,                          Toast.LENGTH_SHORT).show();                 imageView.setImageResource(pics[arg2]);             }         });           // look for the button we set in the view         ImageButton cameraButton = (ImageButton)                 findViewById(R.id.button_camera);         // set a listener on the button         cameraButton.setOnClickListener(cameraListener);      }         // set a new listener     private OnClickListener cameraListener = new OnClickListener() {         public void onClick(View v) {             // open the camera and pass in the current view             takePhoto(v);         }     };      public void takePhoto(View v) {         // tell the phone we want to use the camera         Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");         // create a new temp file called pic.jpg in the "pictures" storage area of the phone         File photo = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "pic.jpg");         // take the return data and store it in the temp file "pic.jpg"         intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photo));         // stor the temp photo uri so we can find it later         imageUri = Uri.fromFile(photo);         // start the camera         startActivityForResult(intent, TAKE_PICTURE);      }      @Override     public boolean onCreateOptionsMenu(Menu menu) {         // Inflate the menu; this adds items to the action bar if it is present.         getMenuInflater().inflate(R.menu.main, menu);         return true;     }      public class ImageAdapter extends BaseAdapter{         private Context context;         int imageBackground;          public ImageAdapter(Context context){             this.context = context;         }          @Override         public int getCount() {             // TODO Auto-generated method stub             return pics.length;         }          @Override         public Object getItem(int arg0) {             // TODO Auto-generated method stub             return arg0;         }          @Override         public long getItemId(int arg0) {             // TODO Auto-generated method stub             return arg0;         }          @Override         public View getView(int arg0, View arg1, ViewGroup arg2) {             // TODO Auto-generated method stub             ImageView imageView =new ImageView(context);             imageView.setImageResource(pics[arg0]);             return imageView;         }     }      // override the original activity result function     @Override     public void onActivityResult(int requestCode, int resultCode, Intent data) {         // call the parent         super.onActivityResult(requestCode, resultCode, data);         switch(requestCode) {         // if the requestCode was equal to our camera code (1) then...         case 1:             // if the user took a photo and selected the photo to use             if(resultCode == Activity.RESULT_OK) {                 // get the image uri from earlier                 Uri selectedImage = imageUri;                 // notify any apps of any changes we make                 getContentResolver().notifyChange(selectedImage, null);                 // get the imageView we set in our view earlier                 ImageButton imageButton = (ImageButton)findViewById(R.id.button_camera);                 // create a content resolver object which will allow us to access the image file at the uri above                 ContentResolver cr = getContentResolver();                 // create an empty bitmap object                 Bitmap bitmap;                 try {                     // get the bitmap from the image uri using the content resolver api to get the image                     bitmap = android.provider.MediaStore.Images.Media.getBitmap(cr, selectedImage);                     // set the bitmap to the image view                     imageButton.setImageBitmap(bitmap);                     // notify the user                     Toast.makeText(MainActivity.this, selectedImage.toString(), Toast.LENGTH_LONG).show();                 } catch(Exception e) {                     // notify the user                     Toast.makeText(MainActivity.this, "failed to load", Toast.LENGTH_LONG).show();                     Log.e(logtag, e.toString());                 }             }           }       }    } 

Layout:

<RelativeLayout 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"     tools:context="com.example.triptych5.MainActivity" >      <ImageView         android:id="@+id/imageView1"         android:layout_width="200dp"         android:layout_height="200dp"         android:scaleType="fitXY"         android:layout_alignParentBottom="true"         android:layout_alignParentLeft="true"         android:layout_alignParentRight="true"         android:layout_alignTop="@+id/button_camera"/>      <ImageButton         android:id="@+id/button_camera"         android:layout_width="230dp"         android:layout_height="235dp"         android:scaleType="fitXY"         android:rotation="-90"         android:layout_alignParentBottom="true"         android:layout_centerHorizontal="true"         android:background="@drawable/middle4" />      <Gallery         android:id="@+id/gallery1"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:layout_above="@+id/imageView1"         android:layout_alignParentLeft="true"         android:layout_alignParentTop="true" />  </RelativeLayout> 

Answer 1

You can simply achieve this by doing:

ImageView imageview = (ImageView) findViewById(R.id.imageView1); ColorMatrix matrix = new ColorMatrix(); matrix.setSaturation(0);  ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix); imageview.setColorFilter(filter); 

Answer 2

This is the Kotlin Version

imageView.colorFilter = ColorMatrixColorFilter(ColorMatrix().apply { setSaturation(0f)})