- Incidentally, we don't pray "to" pictures to intercede. That would be silly silly: art objects don't intercede.
Really?
That is not the only image or icon which is widely regarded to have "powers" -- and if not powers intrinsic to the object itself, then the object be as *special portal* to the entity or heavenly being which the image is understood to represent.
You said -- what is forbidden is idols, with the "veneration" of them (and what they represent) being often so nearly indistinguishable from worship, that even many (Roman) Catholics cannot honestly say of their fellows that idolatry of sorts is not taking place, even though they themselves may well be stopping short of that.
For those whom do stop short --- if they were ever in the neighborhood of the statuary which represents Waldo, Wycliffe, Calvin & Luther, give then a looking over -- and than Thank God for those men's efforts to bring sanity, and restraint away from excesses which human beings are prone towards...like praying to the Virgin of Guadalupe image (for example -- for do any doubt that they would oppose such things?).
Those men are due thanks to God for their having once lived among us, for they all had their own positive effects, in their own times, even if none of them be themselves also without their own limitations, and flaws also -- which must be seen for they are, not for what the RCC found embarrassing to it's own practices and manner of speaking/describing the things of God.