Image rotations
===============

This example shows how to use :ref:`rotate`, :ref:`rot90cw`, :ref:`rot90ccw`, and :ref:`reslice` commands.
First the example rotates input image 90 degrees clockwise, then 90 degrees around :math:`x`-axis using the :ref:`reslice` command,
and finally -60 degrees around vector :math:`[1, 1, 0]` using the :ref:`rotate` command.


::

	def rotations():
		"""
		Demonstrates rotations and re-slicing.
		"""

		# Read image
		img = pi.read(input_file())

		# Rotate 90 degrees clockwise (around z-axis)
		rot90 = pi.newimage()
		pi.rot90cw(img, rot90)
		pi.writetif(rot90, output_file('rotate_90_clockwise'))

		# Reslice (rotate 90 degrees around x- or y-axis)
		top = pi.newimage()
		pi.reslice(img, top, ResliceDirection.TOP)
		pi.writetif(top, output_file('reslice_top'))

		# General rotation.
		# NOTE:
		# - The size of the output must be set to desired value before the call
		#   to rotate function.
		# - The angle is given in radians. Here it is -60 degrees.
		# - The axis is given as a vector and it does not need to be a unit vector.
		grot = pi.newimage(img.get_data_type(), img.get_dimensions())
		pi.rotate(img, grot, -60/180*3.14, [1, 1, 0])
		pi.writetif(grot, output_file('general_rotation'))
		
		
		
.. figure:: figures/rotations_original_90degcw_reslice_top.png
   :scale: 90 %
   :alt: Input image and 90 degree rotations.

   One slice of the input image (left), one slice of the input rotated 90 degrees clockwise (middle), and one slice of the input rotated 90 degrees around :math:`x`-axis using the :ref:`reslice` command. The location of the slice in the rightmost panel is shown with red line in the leftmost panel.
		
		
.. figure:: figures/rotations_general_3d.png
   :scale: 90 %
   :alt: Original and rotated image.

   3D visualization of the original image (left) and the original rotated -60 degrees around :math:`[1, 1, 0]` (right).