The type of media shared through social media channels has shifted from text content to include an increasingly large number of images. Visual traces resulting from people's online social behavior have the potential to reveal insights about our habits, activities and preferences. The role of social network-related factors have been well studied in previous research. Yet, few studies have sought to understand how user behavior in social networks is dependent on the image itself. The goal of my dissertation is to understand how people engage with image content, and I seek to uncover the role of presentation and image content on people's preferences. To achieve this goal, I study the image sharing communities, Flickr, Instagram and Pinterest, using quantitative and qualitative methods. First, I show how colors -- a fundamental property of an image -- could impact the virality of an image on Pinterest. I consider three dimensions of color: hue, saturation and brightness and evaluate their role in the diffusion of the image on Pinterest, while controlling for social network reach and activity. Next, I shift the focus from abstract colors to a higher-level presentation of images. I study the role of filters on the Flickr mobile application as proxies to visual computation. To understand how people use filters, I conduct an interview study with 15 Flickr mobile users about their filter use. I analyze Flickr mobile images to discover the role of filters in engaging users. Presentation is not the only factor that makes an image interesting. To gain deeper insights in what makes an image more engaging in social image sharing sites, I study the images of people on the Instagram network. I compare images of people with those that do not have faces and find that images with human faces are more engaging. I also look at the role of age and gender of people in the image in engaging users. Finally, I examine different content categories, with and without filters, and study the impact of content category on engagement. I use large-scale data from Flickr and interviews with Flickr mobile users to draw insights into filter use and content engagement. This dissertation takes a first step toward understanding content and presentation of images and how they impact one aspect of user behavior online. It provides several theoretical and design implications for effective design, creation and imposition of rules on image sharing communities. This dissertation opens up a new direction for future research in multimedia-mediated communication.

Photography has long been of importance for humans in aspects of community, sharing and documenting. It has previously only existed in analogue format and with larger cameras. We have presently reached a new generation of cameras and photography. The new smaller compact cameras that are provided with most cellular phones take digital images of varying quality and accounts for a large part of photography. With the emergence of social media, photography and social interaction combined came photo applications with different features. In our essay we chose to investigate the immensely popular photo application called Instagram. Our purpose is to identify how it’s being used and what filters do for the usage of it. We have, by conducting user interviews and an observational study, identified that some motifs are more popular than others, that the filter feature and aesthetic pursuit is essential for Instagram usage and that hashtags play an important part regarding “likes” and dissemination.

På Facebook är man författare till sin egen digitala självbiografi. Sociala medier och socialanätverk har gjort det möjligt för användare att kunna forma den bild av sig själv man vill visaomvärlden. Vi har gjort en studie om vilka strategier man använder sig av för att dela bilderoch vad dessa bilder säger om användarens identitet. Med hjälp av tidigare forskning samtvår egen studie bestående av intervjuer och enkäter har vi kommit fram till att man ofta delarbilder för att ta kontakt och känna gemenskap med andra människor/användare. Användarnavi undersökte vill visa den bästa bilden av sig själva samtidigt som användarna vill visa en såverklighetstrogen bild som möjligt. De har inga problem med att modifiera bilden av sigsjälva med att exempelvis ta bort en tagg eller be någon ta bort någon bild som är publiceradpå dem. Vad som visas på deras Facebookprofiler har stor betydelse för användarna. / On Facebook, you are the author of your own digital autobiography. Social media and socialnetworks have made it possible for users to decide how they want to be perceived. We haveconducted a study regarding what strategies people use to share images and what they sayabout the users identities. We have found out through previous research, interviews andsurveys that people often share images to connect with others and socialize. The users westudied wanted to present their best sides and still stay true to their personalities in real life.They have no problems with modifying their self-image by, for example, removing tags orpictures taken of them. What is displayed on their Facebook profile page is very important tothe users.

The smartphone has become an important part of our daily life. It takes advantage of multiple built-in sensors, along with internet connectivity, to provide a variety of services including navigation, weather forecasts, media capturing/sharing, and many more. The smartphone has become a hub for our social interactions, ranging from traditional voice communications through messaging, to online social networking. There are endless possibilities for a new generation of applications that automatically adapts according to users’ social affinities. The key enabler is to understand the social profile of the user and to realize a Social Proximity Indicator (SPI). This indicator of a user’s social profile includes the user’s location, preferences, common friends, frequent interactions among friends, community membership, and many more attributes. This project addresses the exploitation of the user’s smartphone as a detector of these user’s social contexts in order to infer the social proximity between any 2 (or more) people. The goal of this social proximity indicator is to identify the (current) set of smartphone users that would want to participate in an application specific activity, such as media sharing, group conversation, etc. SPI identifies users based on their social interactions and common preferences. Based on this SPI, a photo sharing application is proposed and built for the Android smartphone platform. This application uses multiple physical and virtual sensors (hosted by the user’s smartphone) to determine the context of the user. After inferring this context, the application initiates photo sharing among an identified group sharing this context. The application, as well as the underlying code, theoretical concepts, and results are presented in this thesis. The experiments conducted during this thesis project indicate that it is feasible to build smartphone based social proximity based applications in which proximity incorporates much more than simply physical location, thus going beyond existing applications. / Smartphone har blivit en viktig del av vårt dagliga liv, som drar nytta av de många inbyggda sensorer, inklusive Internet-anslutning, för att ge en mängd olika tjänster. Däribland navigation, väderprognoser, media fånga/delning, och många fler tjänster. Smartphone har blivit kärnan i våra sociala interaktioner. Den erbjuder allt från traditionella röst kommunikation via meddelanden, till sociala nätverk. Det finns oändliga möjligheter för nästa generationens program som kommer att automatiskt anpassar sig till användarnas sociala tillhörighet. Den viktigaste faktorn är att förstå den sociala profilen av användaren genom att använda ett Socialt Proximity Indikator (SPI). Denna indikator på social profil innehåller användarens läge, inställningar, gemensamma vänner, täta samspel mellan vänner, gemenskap medlemskap, och många fler attribut . Detta projekt behandlar utnyttjandet av användarens smartphone som en detektor av användarens sociala sammanhang för att ansluta sig till social närhet mellan några två (eller fler) personer. Målet med denna indikator är att identifiera den (nuvarande) uppsättning av smartphone-användare som skulle vilja delta i någon applikation specifik aktivitet, till exempel mediedelning, gruppsamtal, etc. SPI identifiera användare baserat på deras sociala interaktioner och gemensamma preferenser. En fotodelnings applikation har föreslagits och byggd för Android smartphone -plattformen, baserad på data från SPI. Denna applikation använder flera fysiska och virtuella sensorer (genom användarens smartphone) för att bestämma ramen för användaren. Efter en analys kommer programmet att initiera fotodelning mellan den identifierade gruppen som hittades i analysen. Applikationen, liksom den underliggande koden ,teoretiska begrepp, och resultaten kommer att presenteras i denna uppsats. Experimenten som genomfördes under detta examensarbete tyder på att det är möjligt att bygga smartphone baserad på SPI där närhet innehåller mycket mer än bara fysisk plats. Det gör applikationen unik än de befintliga applikationer.