document image classification: the RVL-CDIP dataset (a collection of
  400,000 images belonging to one of 16 classes).
document layout analysis: the PubLayNet dataset (a collection of more
  than 360,000 document images constructed by automatically parsing PubMed XML files).
table detection: the ICDAR 2019 cTDaR dataset (a collection of
  600 training images and 240 testing images).