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One key decision we made was to have the start screen be the screen where the user takes a picture of the receipt. While that had an impact on learnability, as some users found it hard to navigate from the start screen to "show statistics" or "manage reports", entering a receipt is the most common action done using the interface, and therefore we prioritized the efficacy efficiency of that action. Moreover, after receiving users' feedback at the paper prototype phase, we decided to have less opted for fewer input parameters and allow more whitespace, and to change changed the logic of the interface to make it the interface more intuitive to the user. For example, functions like 'itemize' and 'split receipt' that existed in earlier prototypes were taken out after the users found them confusing, and their benefit to the receipt classification wasn't significant. We . We also included auto-complete capabilities and keyboard input into in the final design. Throughout the design , phase we emphasized simplicity in use, instead of having fancier or over flashier visual cues.
Our final design was very tailored towards an Android phone platform and therefore it relays relys heavily on the 'back' button. We decided not to implement visualize a back button for most pages, instead relying on the back button from on the standard Android phone interface. This design decision cannot be made for an iOS implementation and has also caused some learnability difficulties for users who are used to other phone platforms.
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