I took this quote from Ellel's Evangelical dictionary of the Bible:

The worship of an idol or of a deity represented by an idol, usually as an image. Idolatry, as a form of religious practice, was common in both OT and NT times. Literary and archaeological evidence for the practice has survived from Mesopotamia, Syria-Palestine, Egypt, and from the Roman Empire.

 One of the most distinctive features of Hebrew religion during the OT period was the absence of idolatry. Its practice was prohibited among the Hebrews, and the archaeological evidence indicates that the prohibition was observed for the most part.

 There were two prevalent forms of idolatry in OT times, both banned by the Decalogue: (1) The first commandment prohibited the Israelites from worshiping any other god than the Lord (Exod. 20:3), thereby eliminating the false forms of idolatrous religion practiced in neighboring nations. (2) The second commandment forbade the worship of the God of Israel in the form of an image or idol (Exod. 20:4-6).

 Of the two prohibitions, the latter was crucial to the integrity of Israel's theology. To worship God in the form of an idol would be to reduce God the Creator to the substance of creation (that which was represented in the idol), thereby undermining fundamentally the conception of the transcendent creator God. The idol gave to devotees a sense of the physical proximity of a deity and perhaps also the conviction that the deity's power could be harnessed by human beings. The God of Israel was immanent, but that immanence could not be expressed in physical or tangible form; it remained the essence of faith and of experience.

 Despite the prohibition of idolatry in Hebrew law, it clearly remained a fundamental form of temptation throughout Israel's history, whether in worshiping false gods through their idols or in reducing the worship of the one true God to idolatrous form. Hence, the denunciation of idolatry in its various forms is a recurrent theme in both the law and the prophets (Deut. 7:25-26; 29:16-17; Isa. 40:18-23).

 In NT times idolatry was practiced in various forms throughout the Roman empire and was steadfastly resisted by the early Christian church. It was understood as a sign of human folly (Rom. 1:22-23), representing a perversion of true religion. More frequently, however, the NT writers used the concept of idolatry in a metaphorical sense, particularly with respect to covetousness (Eph. 5:5, Col. 3:5); covetousness is an "idol" by virtue of becoming the immediate focus of a person's desires and "worship," displacing the worship of God.

 In the later history of Christianity, idolatry in the strict sense has continued to be opposed in the terms of the ancient biblical prohibitions. But the continuing danger has more commonly returned in the metaphorical sense delineated in the NT; it is the "worship" (i.e., the total dedication of a person) of that which is seen and tangible, the goals of covetousness, rather than the unseen spiritual being that is God. P. C. CRAIGIE

From this I gather that the operative word is 'worship' not put on a T-shirt.

I hope that helps.

I think that only images used for worship are in fact graven images. That seems to be the consensus of Evangelical Bible Scholars. 

If you think about it, the prohibition against graven images was to prevent people from trying to objectify God, and or reduce Him to something that could be depicted as human.

How the hell did you think that a football jersey qualified as such?