A text also can be pictorial.
Scholars can analyze advertisements, posters, paintings, illustrations, works of art.
When you analyze a text, you give it meaning beyond what the text tells you directly. When you summarize, you essentially report about the contents of the text. But when you analyze a text, you ask questions about it so that you can offer an interpretation of the text. Analysis is the breaking down of something into its component parts. When that something is a text, the reader is examining different aspects of the text.