Vudu, Inc., the folks who brought you the Vudu Box and movie-download service, have announced a new video format that they claim offers better image and sound quality than any other on-demand service.

Dubbed HDX, the new format is supposedly optimized for 40-inch and larger HDTVs video projectors in home theaters. Pixel resolution (1080p) and frame rate (24 frames per second) remain the same as Vudu’s HD format movies, but HDX films will be encoded using Vudu’s new TruFilm technology.

TruFilm consists of four elements: “Psychovisual processing,” which Vudu maintains improves picture quality by enhancing details and removing artifacts in dark regions of the picture. “Color gradient processing” which is designed to tune the picture for display on LCD and plasma televisions, and “statistical variable bitrate” is supposed to encode the film using more or less compression depending on the complexity and degree of motion in each frame. The last element, “film grain preservation,” is designed to match the optical texture of the original film. This last claim is particularly interesting in light of the fact that Vudu’s source material is not film but an uncompressed digital file provided by the studio.

Vudu tells us that movies encoded in HDX format will undergo much less compression, a fact that should definitely improve image quality over the firm’s current HD offerings. Most critics maintain that Vudu’s HD movies look much better than DVD, but that they’re not as impressive as Blu-ray. Less compression, of course, translates to higher bit rates and longer download times on all but the fastest broadband connections.

While Vudu’s standard- and high-definition movies stream over the Internet at bit rates of 2Mb/sec and 3.7Mb/sec, respectively, HDX movies will stream at 9.5 Mb/sec. If your broadband connection can’t keep up with those bitrates, the start of the movie will be delayed until a sufficient portion of the film has spooled to the Vudu’s internal hard drive.

Vudu has encoded 65 of the HD films in its library to HDX and intends to convert the balance—as well as all new HD releases—over time.