Besides collecting pictures of musical instruments and performances, Dr. J.W. Niemeijer amassed a reasonable amount of portraits of composers, musicians and more in general people related to music.
A striking one is the supposed-to-be portrait of Johannes Couchet (1610-1655)* Flemish harpsichord maker active in Antwerp within the school of the Ruckers family. The RKDexplore database has a full record of the painting, with literature as well. Among the pictures here below, also the painted lid of one of the instruments one of his heirs built in 1679.
According to Jan Kosten**, the portrait might have been painted by the painter Gonzales Coques (1614/18-1684) also active in Antwerp at about the same period Couchet was. In many of his paintings, Coques included harpsichords that were likely drawn after actual instruments, possibly by Ruckers or Couchet.
Flemish School_early 17th cent, Portrait of a man said to be Johannes Couchet 
Lid of a Joseph Joannes Couchet_1679 Soth_Lon_22-11-2001
0 syn’ slinckse zij / 8. Apr. 1655
This poem refers to the peculiar shape of the coffin, which hints to the profession of Couchet and his family. More importantly, Huygens reports that inside that “harpsicoffin” the body was not lying on his back, but on the side, since the instrument builder suffered of humpback!
**Jan Kosten, ‘Het portret van de Antwerpse klavecimbelbouwer Johannes Couchet I (1610-1655)’, RKD-Bulletin, extra nummer, juli 2007, p. 15-20.
Anna Bianco 