No, not always. It would be the title of an event. In this case we don't speak about the image and the sound, but generally about these concepts. The article is a demonstrative actually, and this is the origin of artcles in many languages, including the Romance ones, since Latin has no articles, instead Ancient Greek did.
I don't understand what you are referring to. This exercise says...Εικόνα και φωνή." Translation: "Image and voice. " with no reference to colors.
In the sentences that do mention colors, for example, "Αυτό δεν είναι ασπρόμαυρο." the translation is clearly, "This is not white and black."
If you are referring to the suggestion above that this sentence could be phrased in English as "sound and image'" please note that I said it would be added, but not that it would be the main translation.
@pjaysnowden No matter what we do, we'll always have our backs against the wall. Because if the translation were "white and black", there would be a gazillion comments of the 'THIS IS NOT ENGLISH" kind. Now that it is "black and white", we get your kind of comment. Nothing personal, I would rather be reading comments like yours instead of the other kind, but I'm just making a general statement that no course will be able to satisfy everyone at the same time, ever.