An intra-prediction apparatus for extending a set of predetermined directional intra-prediction modes of a rectangular video coding block, each predetermined directional intra-prediction mode of the set of predetermined directional intra-prediction modes being associated with a predetermined direction within a predetermined directional range, the intra-prediction apparatus comprising: an aspect ratio determining unit configured to determine a width and a height of the rectangular video coding block, and to determine an aspect ratio of the rectangular video coding block on the basis of the width and the height; the intra-prediction apparatus characterised in that it further comprises: a complementary angle range determining unit configured to determine a complementary angle range (α) upon the basis of the aspect ratio of the rectangular video coding block, the complementary angle range (α) being associated with a complementary directional range different from the predetermined directional range; a directional intra-prediction mode extending unit configured to select a complementary direction within the complementary directional range, and to add an extension directional intra-prediction mode being associated with the complementary direction to the set of predetermined directional intra-prediction modes; and an intra-prediction unit configured to intra-predict pixel values of pixels of the rectangular video coding block on the basis of the extension directional intra-prediction mode. an aspect ratio determining unit configured to determine a width and a height of the rectangular video coding block, and to determine an aspect ratio of the rectangular video coding block on the basis of the width and the height; the intra-prediction apparatus characterised in that it further comprises: a complementary angle range determining unit configured to determine a complementary angle range (α) upon the basis of the aspect ratio of the rectangular video coding block, the complementary angle range (α) being associated with a complementary directional range different from the predetermined directional range; a directional intra-prediction mode extending unit configured to select a complementary direction within the complementary directional range, and to add an extension directional intra-prediction mode being associated with the complementary direction to the set of predetermined directional intra-prediction modes; and an intra-prediction unit configured to intra-predict pixel values of pixels of the rectangular video coding block on the basis of the extension directional intra-prediction mode. a complementary angle range determining unit configured to determine a complementary angle range (α) upon the basis of the aspect ratio of the rectangular video coding block, the complementary angle range (α) being associated with a complementary directional range different from the predetermined directional range; a directional intra-prediction mode extending unit configured to select a complementary direction within the complementary directional range, and to add an extension directional intra-prediction mode being associated with the complementary direction to the set of predetermined directional intra-prediction modes; and an intra-prediction unit configured to intra-predict pixel values of pixels of the rectangular video coding block on the basis of the extension directional intra-prediction mode.