In the phenomenalism of both the Empiricists of Europe and the Sautrantika Buddhists in India, we find what is often referred to as the "representational" theory of perception (this theory is also found in the Samkhya-Yoga school and in the Vedanta generally). According to the representational theory of perception, we do not actually directly see objects; rather, we see a representation of the object in our mind, like an imprint of a solid object on a disc of soft wax, as it were. Phenomenalists, such as empiricists and the Sautrantikas, are "realists" in the sense that, 1. what we see when we see these representations are indeed accurate likenesses of objects, and 2. the objects that give rise to representations are indeed real objects existing "outside" in the mind. But there is also sense in which the representationalism of the phenomenalists can be called a kind of "quasi-idealism" insofar as, according to this theory, we do not actually apprehend physical objects when we perceive as much as we apprehend representations occuring in some sort of mental space.
In any case, the representationalism of the phenomenalists contains within it a tendency toward what we have referred to as subjective or epistemological idealism. In subjective idealism, the "outside" object is dropped altogether as unnecessary and redundant; all that exists are mental events.
In the case of the West, this development is due to pressure contained in the "logic" of epistemological foundationalism. In a sense, as Wittgenstein noted, Berkeley was the most consistent of the British empiricists in that he submitted himself to the force of this "logic." For his own part, Hume simply could not accept this outcome in toto, even though the conclusion of subjective idealism was logically compelling to him. At the end of the day, as he admits, he goes home and plays billards and does not question the existence of the balls on the table. The development of epistemological idealism in the Yogachara is more difficult to trace. Here, the pressure appears to have come from two directions: one logical and the other soteriological. In the case of the former, it appears to have involved the resolution of certain difficulties left over from the Abhidharma analysis of mental events.
Another form of idealism -- situated "between" subjective idealism and absolute idealism, and yet different from both -- also indirectly develops out of phenomenalism: transcendental idealism. Transcendental idealism also holds that we do not directly perceive objects as they are in themselves; rather, we only perceive the phenomenal appearance of the object. This phenomenal appearance consists of raw perceptual data as well as certain conceptually constructed elements fused with sense data. Transcendental idealists hold that our cognitive make-up is such that conceptual construction forms an integral part of all mental events, including perception. It represents a kind of compromise with "realism" -- in that it holds that the perception of the world is an objective event that has objective validity -- but, technically and strictly speaking, unlike phenomenalism, it is not a form of realism but a form of idealism.
Examples of transcendental idealism include the philosophy of Kant, and posibly the philosophy of the great Buddhist logicians, Dignaga and Dharmakirti. Like Kant, Dignaga and Dharmakirti hold that all perception involves a degree of conceptual construction (vikalpa; kalpana). But like Kant, they also hold that the "thing in itself," or what they call the pure particular (svalakshana), is the basis of all perception, even though it is never directly perceived. The school of thought initiated by Dignaga and Dharmakirti eventually became the dominant school of Buddhist philosophy in India. It reflects a synthesis of Yogachara and Sautrantika thought with logicism.
Let us now return to the Yogachara idealism. It is generally thought by scholars that there are two forms of Yogachara thought. (See http://ccbs.ntu.edu.tw/FULLTEXT/JR-PHIL/ew27052.htm) This distinction leads us to the final form of idealism we shall look at here: absolute idealism. Absolute idealism, as a generalized point of view, holds, 1. that "spirit" (consciousness, mind, etc.) is in some sense more real than "matter"; and 2. that the material world is in some sense an "emanation" from pure spirit. Though we find this idea in the modern West in the philosophy of Hegel, and in the midst of the development of Buddhist philosophy and logic, this perspective actually harkens back to very ancient ideas of cosmogony, in particular to the theistic cosmogonies of ancient Greece and India that viewed God as, not only the instrumental, but the immanent material cause of the world (the "stuff" out of which the world is created.)
In the case of the second stream of the Yogachara, the world is seen as the "projection" (pratibhasa) of mind (vijnana; citta). We find a similar idea in pre-Shankara Advaita Vedanta as well, for example, in the Gaudapada Karikas, which describes the world as due to the "vibration" (sphurana) of mind or consciousness (manas; vijnana; citta). We also find this teaching in Kashmiri Shaivism, which consciously attempts to re-instate emanationist ideas of the older Shaivas.