As the dim shape in the wallpaper becomes clearer, what does the narrator realize it is?

Day after day, the narrator watches the wallpaper, and she realizes that there is a figure, "like a woman, stooping down and creeping about behind that pattern."  At first, she hates the wallpaper and its horrible color, pattern, and smell.  She associates it with illness and decay and death.  As she becomes more and more unhappy in her attic prison, a place with bars on the windows, a bed nailed to the floor, and a...

Day after day, the narrator watches the wallpaper, and she realizes that there is a figure, "like a woman, stooping down and creeping about behind that pattern."  At first, she hates the wallpaper and its horrible color, pattern, and smell.  She associates it with illness and decay and death.  As she becomes more and more unhappy in her attic prison, a place with bars on the windows, a bed nailed to the floor, and a gate at the top of the stairs to prevent her from leaving, she realizes that the wallpaper has "bars" too, bars that trap the woman in the paper.  By day, this woman is "subdued, quiet," and it keeps the narrator "quiet by the hour." 

Shortly after she begins to see this woman, trapped in the paper, she realizes that "Life is very much more exciting now than it used to be" because she has something to occupy her mind, something to think about and reflect on.  She now begins to feel as though she is improving as a result of the wallpaper.  She claims to see the woman "creeping" behind the bars in the paper, just as she admits to "creeping" all over her own room, but only "by daylight" (when she's alone because her husband is away).  Finally, she realizes that the woman is shaking the bars on the wallpaper just as she, herself, begins to help her by tearing the paper down.  In the end, she realizes that she "[came] out of that wall-paper" -- she feels that she is successfully freed this woman from the wallpaper, and now she believes that she is actually the woman she freed.