Visual images are often used in science communication activities and events for different purposes and in different contexts. However, there is limited research on this area and the decision made for choosing a visual image often relies on common sense or the personal judgement of a science communicator. Previous studies have highlighted potential effects with respect to a specific visual image property. This research aims to expand on existing research by examining visual images and their accompanying written texts utilised in 'encountered' science communication events. A case study approach was adopted to examine selected examples occurring within the years 2014-2018. The analysis is based on discourse analysis of the visual image and accompanying written texts which scrutinises the construction of an intended concept or ideology. The analyses of exemplified cases demonstrate several relationships between a visual image and accompanying elements to express an ideology. As such, there are four distinct, though occasionally overlapping, ways accompanying elements contribute to a visual image namely identification, expansion, implication, and reinforcement. The case studies then serve as the basis for synthesising the research findings in a science communication context. The findings indicate that a visual image or series of visual images can increase the opportunity for initial engagement through large physical size or occupied space, colour and brightness, recognisable elements, and the coherence with other collaborative visual images. It may also prolong the initial attention by being part of a series or continuation, displaying aspects of relevance or applicability, resonating with emotions, and being intriguing or challenging with respect to the interpretation. With regards to achieving learning outcomes, textual/verbal information is often required for the audience to process scientific knowledge relevant to the images. The interdependent combination of visual and textual/verbal information may enable the promotion of an attitude/value or ideological standpoint. Meanwhile, the use of a visual image can provide enjoyment or inspiration, as well as support the improvement of visual skills by default. These findings are summarised as a guide for science communication practitioners to use in the selection of visual images. In addition, there is a suggestion that the use of a visual image analysis framework could be a useful tool for a science communicator in selecting visual images for use in science communication.