'The Witches' as a Film

Today I have watched "The Witches" film based on Roald Dahl's book.  It is okay but skims over some parts of the book.  The Grand High Witch is tall in the film, but only 4 foot in the book.  I feel her face was horrible, but in the book it said it looked like it had worms eaten away at it.  I want to look making it have worms in the face.