Huber's picture is clearly a fragment of a larger composition. On the far right the hand of the blessing Christ is visible, as is part of his robe and his foot, but the rest of his figure has been lost. The subject of Christ taking leave of his Mother before departing for Jerusalem and death on the cross was sometimes included in series of the Life of Christ or the Virgin. This painting, however, like Altdorfer's picture of 'Christ taking leave of his Mother' (also in the National Gallery), may always have been a single panel rather than part of an altarpiece. The two paintings may also be very close in date, from about 1520.
You are all set!
Your first Culture Weekly will arrive this week.