Two stamps from the German Democratic Republic commemorating Expovita, an expo for sports and cultural recreation.
I'm not sure what sporting event or competition this stamp is for, but the abstract geometric background the mix of spot color + halftone printing are really doing it for me. "Bưu chính" means postal and that's all I can tell you. If anyone has any information on this one, please share it!
Two from the incredibly prolific Hungarian designer Joseph Vertel. Buildings, thick lines, and grimy halftone dots... this guy knows what I like in a postage stamp design. So good.
See much much much much more work from José Maria and his son Pepe at cruznovillo.com
Two 1970s stamps showcasing some super trippy op-art styles. One from Finland and one from the grand-daddy of the genre, Hungarian-French artist Victor Vasarely!