Catechism of the Catholic Church §2132 — excerpt
The Christian veneration of images is not contrary to the first commandment which proscribes idols. Indeed, "the honor rendered to an image passes to its prototype," and "whoever venerates an image venerates the person portrayed in it."
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: St. Basil, De Spiritu Sancto 18, 45: PG 32, 149C · Council of Nicaea II: DS 601 · Council of Trent: DS 1821-1825 · Vatican Council II: SC 126 · LG 67 · St. Thomas Aquinas, STh II-II, 81, 3 ad 3