My own introduction to the theology of the icon initially came through a two volume set by Leonid Ouspensky, The Theology of the Icon, which is published by St. Vladimir's Seminary Press, an Eastern Orthodox publishing house which produces some very fine and interesting titles, inclusive of another interesting title on icons by him, The Meaning of Icons which is co-authored with Vladimir Lossky -- author of The Mystical Theology of the Eastern Church. A second similar set that I should also mention, though one which I was introduced to years later, is Constantine Cavarnos' Guide to Byzantine Iconography published by the Institute for Byzantine and Modern Greek Studies. (See my review of this title, first published in Logos: A Journal of Eastern Christian Studies.)
Two particularly important iconographic masters who I have always found of great interest were Andrei Rublev and Theophanes the Greek. Here is some of their work.
Andrei Rublev
Theophanes the Greek
Of course, in studying the theology of the icon and considering the Eastern iconographic tradition, while there is great interest in looking at particular icons in their various symbolic and theological details (and I would highlight the festal icons here in particular), one must also consider them within their ecclesial and liturgical context in order to gain the fullest possible appreciation and understanding of this tradition.
(Image source)
(Image source)
Those familiar with this tradition will know that, while there is some variance in this regard, the placement of the particular icons of a Byzantine church have a rich theological symbolism. Icons, in short, are not merely decorative in the Eastern tradition.
At some point, it would certainly be an idea to speak on each of these matters more in depth. For the moment, however, I simply wished to offer this very most cursory set of thoughts on the rich iconographic tradition of the Christian East.