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Tapping the “Search” field at the top right brings up the keyboard and a filter bar. The albums view does not change, but albums not matching the search terms are hidden as the user types. The filter bar presents four ways to search: by the name of the album, by the creator of the album (the friend who uploaded it), by the people tagged in the album (in which case the filter field autocompletes the names of friends, and multiple friends can be entered), and by all of the above properties at the same time. Note that searching for people tagged in the album displays albums with at least one photo with the entered people tagged; the user has to open the album and either scroll through the photos or re-enter the search to see just the photos of the chosen people. Also note that Search in the Photo Grid view behaves in the same manner as Search in the Albums view.
Photo Grid View
This view displays photos in a particular album as a grid, with a thumbnail of each photo and its caption (if available). Tapping or pinching on a photo displays that photo in Photo view. The user can search in this view just as in Albums view, and the user can choose to share the entire album via a button in the toolbar (tapping the button pops up the menu shown in this sketch). The user can go back to the Albums view by either tapping the “Back” button, or choosing a new tab at the bottom.
Storyboard
After logging into PhotoBook, Charles clicks on the “Friends” tab and scrolls through the list. He comes across Jennifer’s name and nervously decides to tap on the gorgeous thumbnail of her to see her photos. 
Charles scrolls through the photos Jennifer is in and comes across a photo with a very worrisome caption, so he pinches on the photo to take a closer look
Charles scrolls through the photos Jennifer is in and comes across a photo with a very worrisome caption, so he pinches on the photo to take a closer look. 
He sees Brian with Jennifer and gets very worried. He confirms that it is really Brian noticing that Brian’s name in the “In this photo” section.
Charles wants to see all photos of Jennifer and Brian together so he can confirm his horrifying suspicions, so he first clicks Back to see photos of Jennifer.
Then he taps on “All Albums” and taps on the search field. He then taps on the “Tagged” filter. Finally, he enters Jennifer and Brian (which are helpfully autocompleted). He finds 13 albums that contain photos of Jennifer and Brian (note that only certain photos in each displayed album contain Jennifer and Brian, and perhaps only a subset of those photos contain them together).
Charles notices an album called “Mountain Trip” and recalls that Brian had recently gone to ski and sled without telling Charles. Charles suspiciously taps on the album to open it.
Charles scrolls through the photos to find photos that might contain Brian and Jennifer together. (Note that, instead of visually looking through the thumbnails, he could have also chosen to search within the album.) He finds a worrisome photo with the caption “Sledding” and taps to take a closer look.
Charles sees Brian and Jennifer together and is outraged. He opens the share menu and chooses “Email.”
The email composition box appears over the photo, and Charles types an angry email to his friend Donovan to try to get some answers. The incriminating photo is automatically attached.
Advantages
Learnability:
Overall, this design presents a very learnable interface. First, it follows the metaphor of the physical album quite closely; PhotoBook initially displays many albums. Then, the user can tap or pinch on album to open it. Finally, the user can tap or pinch on a photo to pull it out of the album to take a closer look. It is also externally consistent; it is similar to the interfaces of many other photo organizing applications with which users are likely familiar, including iPhoto, the iPad’s “Photos” app, and Facebook’s website. Additionally, it uses standard interface widgets found throughout other iPad applications. Finally, although the photo browsing and searching experience is divided into two views - Album view and Photo List view - these views behave in the same manner. Specifically, the user can tap and pinch on thumbnails to open them in either view, and the user can filter the displayed thumbnails using the same filter interface.
Visibility: The state of the interface is generally quite visible. Almost the entire screen is occupied by content, namely thumbnails of photos, and thus there is little “chrome” that gets in the users way. Every thumbnail is tappable or pinchable, and is thus directly manipulable. Additionally, every view has a title that indicates what is being displayed.
Efficiency: The grid design of this interface allows many thumbnails (about 9-12) to be displayed on the screen at a time. Thus, the user can quickly scan the screen to find interesting albums and photos, without excessive scrolling.
Error prevention and correctioncorrection: Since PhotoBook focuses on content consumption, rather than content creation, many classes of errors found in other applications are not applicable in our designs. It is, for example, impossible to accidental delete a photo or tag the wrong person in a photo, since deleting and tagging are not supported features. Thus, this design prevents users from making serious errors. There are, however, several minor errors that can occur. For example, if the user enters the wrong search term in the filter field, she can simply use the standard backspace key to correct the error and observe the new results appear live, confirming that she has entered the correct terms. Additionally, in this design, if the user is searching for a particular photo, she has to open albums that she thinks might contain that photo. However, if she chooses the wrong album, then this interface offers a “Back” button to return to the Album view, with her scroll position maintained, so she can try another album.
Disadvantages
Learnability: This design’s greatest strength lies in its learnability. However, as expected, the primary instances where the design’s learnability breaks down is where the design breaks the physical album metaphor. For example, the “Friends” tab displays an album for each friend containing the photos that friend is in. This provides a powerful organizational and searching tool, but most people would not copy all of their photos and make an album for each of their friends. Thus it may be unclear what these albums actually contain.
Visibility: The paginated nature of this design poses visibility issues. Tapping on an album completely hides the rest of the albums, and tapping on a photo completely hides the rest of the photos. Thus, the interface introduces a “Back” button to restore the previous state, but the user must recall the last thing they were doing to know what to expect when she hits the back button.
Efficiency: Although this design allows a maximal amount of content to be displayed on the screen at a time, it exhibits poor efficiency for many tasks. First, when exploring many albums, the user must close the album they are currently viewing before she can open another one. This involves hitting the back button (which provides a small target area that may be distant from the user’s finger if she is scrolling through photos), then visually searching through the album thumbnails to find the next interesting album.
Second, this interface makes some searches difficult. It is easy to search for an album by its name simply by typing the name in the filter field in “All Albums” view, and it is easy to find, for example, photos in a particular album in which a friend is tagged by opening the album then using the filter field. But, as the scenario made apparent, it is much more difficult to find all photos containing two or more people together. The user must search for those two people in “All Albums” view (since “Friends” view will only contains albums only for a single friend), then open each resulting album to see the photos in that album, then find the specific photos that contain the two desired people. Since the interface for exploring and searching is the same in this design, other types of complex searches are difficult and time consuming.
Error prevention and correction: As noted above, it is rare for users to be able to make a serious error in PhotoBook. Navigation errors, however, may be common when the user is searching for a particular photo and has to look through several albums. While it is easy to correct this error by using the “Back” button, the other designs mentioned below make the error less likely and faster to recover from. Specifically, the user does not need to “open” albums in the Side-scroll design (Design 2), and thus will not open the wrong album by mistake. In design 3, opening an album is less of a commitment than in this design, since instead of being moved to an entirely separate page, some other albums remain visible when an album is opened, and an album can be closed by simply tapping anywhere outside the album.
Design 3
Storyboard
Charles has downloaded Photobook, and wants to browse photos. He opens the app and the Facebook login page opens. Charles already has a Facebook account, and enters his login details.
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