Android: Converting a Bitmap to a Monochrome Bitmap (1 Bit per Pixel)

Question

I want to print a Bitmap to a mobile Bluetooth Printer (Bixolon SPP-R200) - the SDK doesn\'t offer direkt methods to print an in-memory image. So I thought about converting

Answer 1

You should convert each pixel into HSV space and use the value to determine if the Pixel on the target image should be black or white:

  Bitmap bwBitmap = Bitmap.createBitmap( bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.RGB_565 );
  float[] hsv = new float[ 3 ];
  for( int col = 0; col < bitmap.getWidth(); col++ ) {
    for( int row = 0; row < bitmap.getHeight(); row++ ) {
      Color.colorToHSV( bitmap.getPixel( col, row ), hsv );
      if( hsv[ 2 ] > 0.5f ) {
        bwBitmap.setPixel( col, row, 0xffffffff );
      } else {
        bwBitmap.setPixel( col, row, 0xff000000 );
      }
    }
  }
  return bwBitmap;