This passage is taken (with minor variations) from John Philoponus, Commentary on Aristotle's De anima 5.34-6.10. See also beta 437, whose continuation this text is.
[1] In Philoponus’ text it is clear that these faculties of the soul are “irrational faculties” (see 5.34). In fact, both appearance (φαντασία ) and perception (αἴσθησις ) are, according to Aristotle (Met., 980a21-b27), common to both human beings and irrational animals.
[2] Aristotle defines imagination as “a movement (or change: κίνησις ) produced by a perception (or sensation: αἴσθησις ) in actuality” (De anima 429a1-2; De insomniis 459a17-18). See also De an. 428b11-16, where it is pretty clear that since imagination is a sort of movement that cannot be produced without sensation, and since the movement is produced by a sensation in actuality (and this movement must be similar to sensation), imagination cannot exist without sensation, neither can it exist in things lacking sensation.
[3] For the well-known distinction between passive and active intellect, see Aristotle, De an. 3.5. Perhaps in this context Philoponus is not specifically making reference to the mentioned distinction, but to the fact that, in accordance with Aristotle (De an. 3.4), the part of the soul by means of which the soul knows and thinks (φρονεῖ ) -- what he calls “intellect” (νοῦς ), De an. 429a17; 22-23 –- is nothing actually before it starts thinking (429a24). That is what should be understood by “passive intellect” in this context. Now Aristotle also clarifies that the impassivity of the intellect must not be identified with the impassivity of the sense-perception (αἴσθησις ): while the sense loses its power to perceive if the sensible thing has been too intense, the intellect, when it has been thinking intensely, is not less but more capable of thinking of inferior things. And the reason for this is that the faculty of perception, Aristotle goes on to argue, depends upon the body, while intellect is separable (De an.429b3-5).
[4] Probably he is making reference to the active intellect which, in being impassive and substantially actuality, acts upon what is passive (De an. 430a17-19).
[5] For Aristotle the mind or intellect is something simple and impassive, so it is somehow potentially all the objects of thought. By contrast, in actuality the mind is none of them until it starts thinking. On the other hand, insofar as thinking is analogous to perceiving (429a13-14), it will be acted upon by the object of thought. This part of the soul is passive, but able to receive the form and, eventually, it is potentially like the form, though not identical with it (De an. 429a15-b24).
[6] See Aristotle, De an. 429a2-4, where he reminds us of the fact that, since sight is the main sense (Met. 980a2-6), the name "imagination" or “appearance” (φαντασία ) derives from “light” (φάος ), because without light nothing can be seen, and so nothing can appear, either.
[7] This refers to the well-known distinction between proper (or peculiar) and common sensible (or perceptible; see De an. 418a7-25). This is Aristotle’s definition of an ἴδιον αἰσθητόν : “I call ‘peculiar’ what cannot be perceived by another sense, and that about which it is not possible to be deceived; for instance, sight in respect of color, hearing in respect of sound, taste in respect of flavor” (418a11-13).