Here it is:

We believe that man was created pure and perfect in the image of God, and that by his own guilt he fell from the grace which he received, and is thus alienated from God, the fountain of justice and of all good, so that his nature is totally corrupt.

From Article 9.

It matches what Calvin wrote in the 1536 edition of the Institutes:

In order for us to come to a sure knowledge of ourselves, we must first grasp that Adam, parent of us all, was created in the image and likeness of God. That is, he was endowed with wisdom, righteousness, holiness, and was so clinging by these gifts of grace to God that he could have lived forever in Him, if he had stood fast in the uprightness God had given him. But when Adam slipped into sin, this image and likeness of God was canceled and effaced, that is, he lost all the benefits of divine grace, by which he could have been led back into the way of life

And he said it again in the final 1559 edition:

If man had no title to glory in himself, when, by the kindness of his Maker, he was distinguished by the noblest ornaments, how much ought he to be humbled now, when his ingratitude has thrust him down from the highest glory to extreme ignominy? At the time when he was raised to the highest pinnacle of honor, all which Scripture attributes to him is, that he was created in the image of God, thereby intimating that the blessings in which his happiness consisted were not his own, but derived by divine communication. What remains, therefore, now that man is stripped of all his glory, than to acknowledge the God for whose kindness he failed to be grateful, when he was loaded with the riches of his grace? Not having glorified him by the acknowledgment of his blessings, now, at least, he ought to glorify him by the confession of his poverty (2.2.1)

Like Tolkien once wrote about the danger of setting your feet on the path outside your door, reading Calvin and the early Reformers can be quite unsafe.

You never know where it may lead.