src/test/scripts/applications/nn/component/im2col.dml

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source("src/test/scripts/applications/nn/util.dml") as test_util
source("scripts/nn/util.dml") as util


im2col = function() {
  /*
   * Test for the `im2col` and `col2im` functions.
   */
  print("Testing the im2col and col2im functions.")

	# Generate data
  C = 3  # num channels
  Hin = 5  # input height
  Win = 5  # input width
  Hf = 3  # filter height
  Wf = 3  # filter width
  stride = 2
  pad = (Hin * stride - Hin + Hf - stride) / 2
  Hout = as.integer(floor((Hin + 2*pad - Hf)/stride + 1))
  Wout = as.integer(floor((Win + 2*pad - Wf)/stride + 1))
  x = rand(rows=C, cols=Hin*Win)

  # pad
  x_pad = util::pad_image(x, Hin, Win, pad, pad, 0)

  # im2col
  x_cols = util::im2col(x_pad, Hin+2*pad, Win+2*pad, Hf, Wf, stride, stride)

  if (ncol(x_cols) != Hout*Wout) {
    print("ERROR: im2col does not yield the correct output size: "
          + ncol(x_cols)+" (actual) vs. "+Hout*Wout+" (correct).")
  }

  # col2im
  x_pad2 = util::col2im(x_cols, C, Hin+2*pad, Win+2*pad, Hf, Wf, stride, stride, "none")

  # Equivalency check
  equivalent = test_util::all_equal(x_pad, x_pad2)
  if (!equivalent) {
    print("ERROR: im2col and then col2im does not yield the original image.")
  }
}

im2col()