title: I want to set Brightness of an image on SeekBar OnProgres change event in Android?
body: <p>I want to set Brightness of an image on SeekBar OnProgres change event?
  I am showing an image in imageview and below that there is an SeekBar to change the Brightness of an image.</p>
  
  <p><strong>1)</strong> I am using following function to set brightness</p>
  
  <pre><code>private static void setBrightness(ColorMatrix cm, float contrast) {
          float scale = contrast + 1.f;
             float translate = (-.5f * scale + .5f) * 255.f;
          cm.set(new float[] {
                 1, 0, 0, 0, translate,
                 0, 1, 0, 0, translate,
                 0, 0, 1, 0, translate,
                 0, 0, 0, 1, 0 });
      }
  </code></pre>
  
  <p><strong>2)</strong> I was able to set brightness of an image using following code</p>
  
  <pre><code>@Override protected void onDraw(Canvas canvas) {
          Paint paint = mPaint;
          float x = 20;
          float y = 20;
          float[]pos={5,5};
          canvas.drawColor(Color.WHITE);          
          paint.setColorFilter(null);
          canvas.drawText("Original Image", 5,20, paint);
          canvas.drawBitmap(mBitmap, x, y, paint);
  
          ColorMatrix cm = new ColorMatrix();
  
          mAngle += 2;
          if (mAngle &gt; 180) {
              mAngle = 0;
          }
  
          //convert our animated angle [-180...180] to a contrast value of [-1..1]
          float contrast = mAngle / 180.f;
  
          canvas.drawText("Brightness", 5,y + 60, paint);
          setBrightness(cm, contrast);//Brightness
          paint.setColorFilter(new ColorMatrixColorFilter(cm));
          canvas.drawBitmap(mBitmap, x ,y + mBitmap.getWidth() + 10, paint);                          
  
          invalidate();
      }
  </code></pre>
  
  <p><strong>3)</strong> Now I want to change the brightness of an image on SeekBar OnProgress change event, but for that I require to have an relationship between ColorMatrix and Bitmap.</p>
  
  <p>Because I don't want to draw an image I want to modify an existing image. i.e. I am showing an image in imageview and below that there is an SeekBar to change the Brightness of an image.</p>
  
  <p>Please help me to change the Brightness of an image onSeekBar Progressed change event.</p>