Image Processing – Image Flipping / Mirroring

This technique is basically same as rotation, however, it transforms rotation with a reverse direction.

– For vertical flipping: [ x = x, y = y * -1 ]

– For horizontal flipping: [ x = x * -1, y = y ]

By using matrix transformation, we’ll get nice results:

Original Image

Vertical Flipping

Horizontal Flipping

Here the implementation:

	// type definition
	public static final int FLIP_VERTICAL = 1;
	public static final int FLIP_HORIZONTAL = 2;

	public static Bitmap flip(Bitmap src, int type) {
		// create new matrix for transformation
		Matrix matrix = new Matrix();
		// if vertical
		if(type == FLIP_VERTICAL) {
			// y = y * -1
			matrix.preScale(1.0f, -1.0f);
		}
		// if horizonal
		else if(type == FLIP_HORIZONTAL) {
			// x = x * -1
			matrix.preScale(-1.0f, 1.0f);
		// unknown type
		} else {
			return null;
		}

		// return transformed image
		return Bitmap.createBitmap(src, 0, 0, src.getWidth(), src.getHeight(), matrix, true);
	}

Hope you like it!

Cheers,
Pete Houston