Group Photo Row Calculator App

I'm looking to build a web-based app to help calculate how many people in each row of a group photograph, specifically for event gatherings. The app should be compatible with both desktop and mobile browsers. Key Features: - Ability to process event gathering photos and determine the number of people in each row. - Integration to point to an already produced slide for that result. Ideal Skills and Experience: - Experience in web app development - Responsive design skills for both desktop and mobile platforms - Backend development skills to manage and store data inputs I'm looking for someone who can create a user-friendly, efficient tool for this purpose. Please provide examples of similar work done.