Best Upscaling Receiver How Does Video Upscaling Works? Can It Really Upscale To 1080p?

How does video upscaling works? Can it really upscale to 1080p? - best upscaling receiver

I saw the home theater receiver and DVD player with video upscaling, and says he can without any 1080p input. Are they really capable of luxury my standard DVD movie in 1080p? After upscaling DVD movies that tries to close on Blu-ray HD movie?