rescale_image
================================================

.. py:function:: petpal.preproc.image_operations_4d.rescale_image(input_image: ants.core.ANTsImage, rescale_constant: float, op: str = '/') -> ants.core.ANTsImage

   Rescales a 3D or 4D ANTsImage intensity values by performing division or
   multiplication with a given constant.

   This function supports two operations: dividing the input image by a
   rescale constant or multiplying it by the constant. Division is only
   allowed with a positive rescale constant to avoid invalid operations.
   The operation is applied element-wise across the image data.

   :param input_image: Input image, given as an ANTsImage object.
   :type input_image: ants.core.ANTsImage
   :param rescale_constant: The constant to rescale the image intensities. For division (`op="/"`),
                            this value must be greater than zero.
   :type rescale_constant: float
   :param op: Operation to perform, either `'/'` for division or `'*'` for
              multiplication. Default is `'/'`.
   :type op: str, optional

   :returns: *ants.core.ANTsImage* -- The rescaled ANTsImage with updated intensity values.

   :raises AssertionError: If `op` is not one of `'/'` or `'*'`.
   :raises AssertionError: If division (`op="/"`) is requested, but `rescale_constant` is not greater than zero.

   .. rubric:: Example

   .. code-block:: python

       import ants
       from petpal.preproc.image_operations_4d import rescale_image

       # Load a sample ANTsImage
       input_img = ants.image_read('example_image.nii')

       # Rescale intensities by division with a constant (e.g., 2.0)
       rescaled_img = rescale_image(input_image=input_img, rescale_constant=2.0, op='/')

       # Rescale intensities by multiplication with a constant (e.g., 1.5)
       rescaled_img = rescale_image(input_image=input_img, rescale_constant=1.5, op='*')