2dehands.be is a Belgian online auction website owned by eBay. To make potential customers aware how many cars are being sold on their website, the concept was developed to show all the cars of the website in one big image. Among the thousands of cars, a few cars2dehands.be branded cars were hidden in the grid. Whoever was able to find this had a chance to win the opportunity to get a chauffeur and a car for one day.
The website is built using the deepzoom viewer OpenSeadragon. This works similar to map applications by using tilesets to offer smooth zooming and panning behavior.
The large image is updated every hour by first syncing and retrieving all the car images from the website, then all the image thumbnails are cropped and merged together using ImageMagick. As a last step, VIPS is used to generate the tileset that is usable in OpenSeadragon. The final generated tileset is about 331MB large. This meant that ImageMagick and VIPS had to be tuned for optimal performance and memory usage.