The present paper deals with the production of a multimodal news item from an ethnographic perspective, aiming at fully understanding the role played by news values, i.e. shared criteria for news selection, in newsroom argumentation. The news item we consider is the picture news from Corriere del Ticino, the main Italian-language newspaper in Switzerland. As the Italian name fototesto says, this news item combines a verbal and a photographical component, presenting the journalists with particular challenges in its selection. To shed light on this production process, we take as a case study a picture news on eco-friendly heat distribution and the editorial conference leading to its choice, which took place on January 24, 2013. We analyze the interaction from the viewpoint of argumentation theory, combining Pragma-Dialectics (van Eemeren and Grootendorst) and the Argumentum Model of Topics (Rigotti and Greco Morasso 2009, 2010, under review), and unravel the reasons behind choices in content and form taken collaboratively by the journalists.