code: def testFlipOnlyImage(self):
      # No changes to image or boxes when no flip is specified.
      image = self._gen_image(100, 100, 3)
      not_flipped_image, _ = self._flip_image(image)
      self.assertAllClose(not_flipped_image, image)
  
      # Test flipped image that original first column is equal to the last
      # column of the flipped one.
      image = self._gen_image(100, 100, 3)
      flipped_image, _ = self._flip_image(image, left_right=True)
      self.assertAllClose(flipped_image[:, 0], image[:, -1])
      self.assertAllClose(flipped_image[:, 1], image[:, -2])
  
imports: import numpy
  import tensorflow
  from easydict import EasyDict
  from luminoth.utils.image import resize_image, flip_image, random_patch, random_resize, random_distortion, patch_image
  from luminoth.utils.test.gt_boxes import generate_gt_boxes
label_desc: Use image node_id 12 for calling the ImageTest obj's underlying member method code with example usage: obj.testFlipOnlyImage() without return types