A high definition upconverter or HD upconverter, is a device that allows DVD signals to be transferred directly to an HDTV (high definition television) without intermediate analog conversion. This improves resolution and overall picture quality. These devices are also known as DTV upconverters (digital television upconverters).

DVD (digital video disk) is an optical technology that stores audio and video signals in digital format for the clearest reproduction. A digital format is superior to an analog format, the technology used by older televisions and computer equipment. A standard DVD player is designed to broadcast to a standard-definition television and translates the digital output into an analog signal the television can understand.

In the case of digital HDTV, the standard DVD player converts the signal to analog, bumps the resolution from 480 lines per frame up to 1080, then converts the signal back to digital. This results in a certain amount of degradation in picture quality. An HD upconverter eliminates the analog conversion. It transfers the DVD signal by digitally enhancing each frame to match the HDTV high-resolution format. The result is a much crisper, truer image quality with heightened detail and color. Digital noise is eliminated, reducing anomalies like color swirl and graininess.

Some high-end HDTVs have an HD upconverter built in, but many models do not. A stand-alone HD upconverter can be purchased to work with existing DVD players. Other models incorporate the convenience of a DVD player along with the HD upconverter. Some models have advanced features. For example, using an internal microprocessor, an HD upconverter can eliminate flicker from DVDs that are based on 35-mm movies, which are originally shot at a lesser frame rate. The flicker is not apparent until the DVD is played through an HDTV, but an HD upconverter can eliminate this effect.

HD upconverters range widely in price. Professional models used in the film industry cost thousands of dollars, but consumer models are modestly priced. A good HD upconverter with a built-in DVD player can be had for a few hundred US dollars. If upgrading your DVD player, an upconverter model will future proof your investment even if you do not presently own an HDTV.