scripts/builtin/img_posterize_linearized.dml

#-------------------------------------------------------------
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#-------------------------------------------------------------

# The Linearized Image Posterize function limits pixel values to 2^bits different values in the range [0, 255].
# Assumes the input image can attain values in the range [0, 255].
#
# .. code-block:: python
#
#   >>> import numpy as np
#   >>> from systemds.context import SystemDSContext
#   >>> from systemds.operator.algorithm import img_posterize_linearized
#   >>> 
#   >>> with SystemDSContext() as sds:
#   ...     img = sds.from_numpy(
#   ...         np.array([[ 10., 20., 30.,
#   ...                     40., 255., 60.,
#   ...                     70., 80., 90. ]], dtype=np.float32)
#   ...     )
#   ...     result_img = img_posterize_linearized(img, 1).compute()
#   ...     print(result_img.reshape(3, 3))
#   [[  0.   0.   0.]
#    [  0. 128.   0.]
#    [  0.   0.   0.]]
#
#
# INPUT:
# -------------------------------------------------------------------------------------------
# img_in  Input images as linearized 2D matrix with top left corner at [1, 1] (every row represents a linearized matrix/image)
# bits    The number of bits to keep for the values.
#         1 means black and white, 8 means every integer between 0 and 255.
# -------------------------------------------------------------------------------------------
#
# OUTPUT:
# ---------------------------------------------------------------------------------------------
# img_out  Row linearized output images as 2D matrix
# ---------------------------------------------------------------------------------------------

m_img_posterize_linearized = function(Matrix[Double] img_in, Integer bits) return (Matrix[Double] img_out) {
  img_out = (img_in %/% 2^(8 - bits)) * (2^(8 - bits))
}