simulate.py 文件源码

def add_jitter(prj, low=0, high=1):
    """Simulates jitter in projection images. The jitter
    is simulated by drawing random samples from a uniform
    distribution over the half-open interval [low, high).

    Parameters
    ----------
    prj : ndarray
        3D stack of projection images. The first dimension
        is projection axis, second and third dimensions are
        the x- and y-axes of the projection image, respectively.
    low : float, optional
        Lower boundary of the output interval. All values
        generated will be greater than or equal to low. The
        default value is 0.
    high : float
        Upper boundary of the output interval. All values
        generated will be less than high. The default value
        is 1.0.

    Returns
    -------
    ndarray
        3D stack of projection images with jitter.
    """
    from xcor.utils import scale
    from skimage import transform as tf

    # Needs scaling for skimage float operations.
    prj, scl = scale(prj)

    # Random jitter parameters are drawn from uniform distribution.
    ind = np.random.uniform(low, high, size=(prj.shape[0], 2))

    for m in range(prj.shape[0]):
        tform = tf.SimilarityTransform(translation=ind[m])
        prj[m] = tf.warp(prj[m], tform, order=0)

    # Re-scale back to original values.
    prj *= scl
    return prj