Add debug image function and debug augmenter

changelogs/master/added/20191117_debug_images.md

@@ -0,0 +1,13 @@
+# Debug Image Creation
+
+* Added module `imgaug.augmenters.debug`.
+* Added function `imgaug.augmenters.debug.draw_debug_image()`. The function
+  draws an image containing debugging information for a provided set of
+  images and non-image data (e.g. segmentation maps, bounding boxes)
+  corresponding to a single batch. The debug image visualizes these
+  informations (e.g. bounding boxes drawn on images) and offers relevant
+  information (e.g. actual value ranges of images, labels of bounding
+  boxes and their counts, etc.).
+* Added augmenter `imgaug.augmenters.debug.SaveDebugImageEveryNBatches`.
+  Augmenter corresponding to `draw_debug_image()`. Saves an image at every
+  n-th batch into a provided folder.

imgaug/augmenters/__init__.py

@@ -1,3 +1,4 @@
+# pylint: disable=unused-import
 from __future__ import absolute_import
 from imgaug.augmenters.arithmetic import *
 from imgaug.augmenters.artistic import *
@@ -6,6 +7,7 @@
 from imgaug.augmenters.color import *
 from imgaug.augmenters.contrast import *
 from imgaug.augmenters.convolutional import *
+from imgaug.augmenters.debug import *
 from imgaug.augmenters.edges import *
 from imgaug.augmenters.flip import *
 from imgaug.augmenters.geometric import *