The traditional veiling of images during Passiontide (this week and Holy Week) has an interesting history and a profound effect on the Faithful:
"The Gospel reading for Passion Sunday in the Classical Rite (i.e. the
Fifth Sunday of Lent, the start of Passiontide) tells us how Jesus 'hid' Himself from the Hebrews when they attempted to stone him (cf.
John 8:59). According to St. Augustine, at this moment when Jesus hid
Himself from the angry crowd, Christ in fact became invisible to them by
virtue of His Divine nature. To help signify this mystery, holy images
in church are veiled the evening before Passion Sunday. This includes
images of the saints, as it is befitting that if the glory of the Master
is hidden, then His servants should also not appear.
"Indeed, in
the Latin Church, we 'hide' His images for two weeks out of the year in a
spirit of penance and mourning. An acute sadness is felt in the human
heart. We long to be reunited with Him. The veil suggests the discomfort
of being separated from Him. We prepare for the agony and triumph of
the Easter Triduum. Outsiders are intrigued by these little customs.
Children remember them. The Faith is passed on. Let us preserve the
inheritance that has been handed on to us by the wisdom of our
forefathers in the Faith."
According to the article in the Liturgical Arts Journal quoted above, originally the veiling was in white. Read more here.
N.B. Readers might be surprised to see that in the linked article there are veiled images together with elaborate altar flowers. It is a puzzling choice. Given that the vestments are somewhat golden, I suppose the photos might have been taken during one of the solemnities that occur during Lent. Altar flowers are permitted during the solemnities of St. Joseph and the Annunciation though generally prohibited during Lent. The liturgical color for those solemnities is white and where the vestments are white, gold may be substituted.