scripts/builtin/img_translate.dml

#-------------------------------------------------------------
#
# Licensed to the Apache Software Foundation (ASF) under one
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# to you under the Apache License, Version 2.0 (the
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# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
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#-------------------------------------------------------------

# The Image Translate function translates the image.
# Optionally resizes the image (without scaling).
# Uses nearest neighbor sampling.
#
# .. code-block:: python
#
#   >>> import numpy as np
#   >>> from systemds.context import SystemDSContext
#   >>> from systemds.operator.algorithm import img_translate
#   >>> 
#   >>> with SystemDSContext() as sds:
#   ...     img = sds.from_numpy(
#   ...         np.array([[ 10., 20., 30.],
#   ...                   [ 40., 50., 60.],
#   ...                   [ 70., 80., 90.]], dtype=np.float32)
#   ...     )
#   ...     result_img = img_translate(img, 1., 1., 3, 3, 255.).compute()
#   ...     print(result_img)
#   [[255. 255. 255.]
#    [255.  10.  20.]
#    [255.  40.  50.]]
#
#
# INPUT:
# ----------------------------------------------------------------------------------------------
# img_in      Input image as 2D matrix with top left corner at [1, 1]
# offset_x    The distance to move the image in x direction
# offset_y    The distance to move the image in y direction
# out_w       Width of the output image
# out_h       Height of the output image
# fill_value  The background of the image
# ----------------------------------------------------------------------------------------------
#
# OUTPUT:
# --------------------------------------------------------------------------------------------
# img_out  Output image as 2D matrix with top left corner at [1, 1]
# --------------------------------------------------------------------------------------------

m_img_translate = function(Matrix[Double] img_in, Double offset_x, Double offset_y, Integer out_w, Integer out_h, Double fill_value)
 return (Matrix[Double] img_out) {
  w = ncol(img_in)
  h = nrow(img_in)

  # round to nearest integer as fraction is irrelevant for nearest neighbor sampling
  offset_x = round(offset_x)
  offset_y = round(offset_y)

  # index range in input image
  start_x = 1 - offset_x
  start_y = 1 - offset_y
  end_x = max(w , out_w) - offset_x
  end_y = max(h, out_h) - offset_y

  # clip copy region to left and top of input image
  if (start_x < 1)
    start_x = 1
  if (start_y < 1)
    start_y = 1

  # clip copy region to right and bottom of input image
  if (w < end_x)
    end_x = w
  if (h < end_y)
    end_y = h

  # clip copy region to right and bottom of output image
  if (out_w < end_x + offset_x)
    end_x = out_w - offset_x
  if (out_h < end_y + offset_y)
    end_y = out_h - offset_y

  img_out = matrix(fill_value, rows=out_h, cols=out_w)
  if (start_x < end_x & start_y < end_y) {
    img_out[(start_y+offset_y):(end_y+offset_y), (start_x+offset_x):(end_x+offset_x)] = img_in[start_y:end_y, start_x:end_x]
  }
}