This leprosy hospital at Kelet (Pati, Jawa Tengah) was a specialized institution that was founded by the Baptist Missionary organization in 1919.
The picture was taken from the KITLV imagebank, signature 77833. It represents patients and staff of Donorodjo (Gift of the king) of a Javanese lepra colony, north of Pati.

A subsidy of f 34,000was granted for building and equipment (Government Decision 14 January 1916 no. 27). In 1936 the institution reached a capacity of 207 beds and 75,516 nursing days. The subsidy in that year amounted to f 31.385,64. A year lateer the capacity was 196 beds and 71.818 nursing days. The subsidy amounts to f 37.919,10. The Governor General decides to fix the amount per inpatient on f 7,50 per month (Decision of 19 August 1919 no. 38, Staatsblad  1919 no, 532.

See Mededeelingen DVG 1939 (no. 28).

23 Annual Report of the sanatorium Donorodjo, institution of leprosy patients, year 1938:
From: G(eneeskundig) T(ijdschrift) N(etherlands) I(ndies) 1939, 79, afl. 33, 15 August 1939, page 2096:
The sunray installation had regular users. The report states that many patients use the sunray. Under the guidance of a nurse 20 patients at the same time are exposed to the ultraviolet radiation. It is a kind of weak radiation but it is a lasting one. the results have still to be evaluated. It seems that the influence of this therapy for many patients has been positive in that it cures many skin defects. Yet for a few patients even a limited dose of the radiation can be hardly supported, whereas it does not show effects in many cases, except for its psychological influence.

From:  Geneeskundig Tijdschrift voor Nederlandsch-Indië (GTNI) 81 , 42 (1941) 2279-2280: Annual Report 1940 of the Sanatorium of lepra patients “Donorodjo”: In the leprosarium “Donorodjo” the process of differentiation was continued. Patients were divided into groups of similar character, which was possible because of the vastness of the terrain. Most important groups were the “Werkcentrale” , where utensils were produced,  the Agricultural colony and Old Donorodjo : here patients were taken into care when the disease had progressed into the second and third stage.

At present the Rumah Sakit Kelet carries on as a provincial organization. See Paragraph Actual-Leprosy.