The core activity of Leuthardt+Partner encompasses three main areas of focus: 1. **Text**: The company provides text services, including journalism, text creation, and editing. 2. **Image**: Leuthardt+Partner offers photography services, including the processing of photographic materials. 3. **Design**: The company provides design services, such as moderation, PR assignments, and visual design. Overall, the core activity of the company can be described as a combination of communication, media, and creative services.