I have published two and a half thousand high-definition photographs of most of the Borobudur monument, which I have taken during three visits I made to the sanctuary in 2009 and 2013, and these comprise the most complete coverage of the monument available on the internet at present. All the photographs are also free to reuse in other Buddhist and scholarly publications.
One section that was missing up till now were the 160 Karmavibhanga reliefs which are covered over at the base of the monument. It is believed that as the building grew higher the structure became unstable and it was decided to widen the base to shore it up. This would account for why a number of the reliefs were never finished also, leaving a work-in-progress look to them.
The base of the Borobudur temple was dissembled in 1890 to reveal the hidden reliefs and they were photographed at the time by Kassian Cephas. It is copies of these photographs, which are now in the public domain, that are reproduced here. During the restoration the foot encasement was reinstalled covering the Karmavibhanga reliefs. Today, only the southeast corner part is revealed and visible for visitors.
The 160 hidden panels do not form a continuous story, but each panel provides one complete illustration of cause and effect. There are depictions of blameworthy activities, from gossip to murder, with their corresponding punishments. There are also praiseworthy activities, that include charity and pilgrimage to sanctuaries, and their subsequent rewards. The pains of hell and the pleasure of heaven are also illustrated. There are scenes of daily life, complete with the full panorama of life in saṁsāra.
Unfortunately, as with the other reliefs on the monument, although we do know which text they are based on, there is no proper key to their interpretation. Because of this I asked Ven Dhammika to help in providing titles based on the likely subject matter. These are rough titles based sometimes on the whole panel, and at times only on a feature of it, but I do think it will be helpful when viewing the panels. If someone has better suggestions they can also contact me with them.