"She looked at the picture." should be accepted...
I don't agree, because the imperfect tense implies a continued or habitual action, and your translation implies otherwise.
He was looking at the pictures--not accepted 21 Dec. 2018.
L'immagine is singular. But "He was looking at the picture" was also rejected. I have reported that.
Yes I think so
Is this not able to be interpreted as an imperative as well? "Look at the image", where the you is implied?
I don't think so. The second person singular imperatives of "guardare" are "guarda" (informal) and "guardi" (formal), not "guardava".