1080p content is 1920x1080. 4K content is 3840x2160. You just literally double-up the pixel size in each dimension; there's no need for interpolation or anythin

1080p content is 1920x1080. 4K content is 3840x2160. You just literally double-up the pixel size in each dimension; there's no need for interpolation or anything else that will cause blurring. I've been working on an FPGA project that involves 1080p into a 4K monitor over HDMI and it looks very sharp to me, even on high contrast edges with a pretty critical eye.