Display apparatus, source device and display system

A display apparatus includes an orientation detecting portion, a receiving portion and an image processing portion. The orientation detecting portion detects an orientation of an upper part or a lower part of a display screen of a display portion. The receiving portion receives an image signal transmitted from a source device and state information (information showing an orientation of an upper part or a lower part of the transmission image indicated by the image signal and presence/absence of black band parts). The image processing portion applies, to the transmission image, rotation processing such that the orientation of the upper part or the lower part of the display screen coincides with the orientation of the upper part or the lower part of the transmission image, scaling processing, and/or black-band processing for adding or removing black band parts, according to a detection result of the orientation detecting portion and the state information.