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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 an 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 a similar 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 correction: 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 accidentally 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.
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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 users must recall the last thing they were doing to know what to expect when she hits they hit 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 users must close the album they are currently viewing before she they 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.
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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 to occur 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 dDesign 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.
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