First define bounding boxes for a set of background images (see the data folder for how to get background images):
python generation/annotate.py data/background/*.jpg
Then paste other images into the defined bounding boxes:
python generation/generate.py \
--test-stamps generation/stamps/test*.png \
--train-stamps generation/stamps/train*.png \
--image-folder data/backgrounds \
--search-path data/bounding_boxes
Alternatively just use pregenerated data (see the data folder).