All test resources must come from free public domain sources for
copyright reasons.

Test files do not necessarily produce perfect (or even good) OCR
results.

+-------------------+--------------------------------------------------------------------------------+
| File              | Source                                                                         |
+===================+================================================================================+
| graph.pdf         | Wikimedia                                                                      |
+-------------------+--------------------------------------------------------------------------------+
| c02-22.pdf        | Project Gutenberg: https://www.gutenberg.org/files/76/76-h/images/c02-22.jpg   |
+-------------------+--------------------------------------------------------------------------------+
| LinnSequencer.jpg | Wikimedia: https://upload.wikimedia.org/wikipedia/en/b/b7/LinnSequencer_hardware_MIDI_sequencer_brochure_page_2_300dpi.jpg   |
+-------------------+--------------------------------------------------------------------------------+
| congress.jpg      | http://www.baxleystamps.com/litho/meiji/courts_1871.jpg                        |
+-------------------+--------------------------------------------------------------------------------+