For its 4K debut, Warner Bros performed a 8K 16bit scan of the original Technicolor camera negative that served as the basis for the 4K Uhd scan. Mpi colorist Janet Wilson, who has overseen every remaster of The Wizard of Oz for the past 20 years, oversaw this process as well.
It's unclear whether this new 4K transfer will also be used for the inclusive The Wizard of Oz Blu-ray or if the previous Blu-ray transfer will carry forward.
A pair of bonus features will appear on the 4K disc. They are:
Commentary by John Fricke with Barbara Freed-Saltzman,