Loading Screens
From Hercules Wiki
Loading screens are graphics, that are shown when the client is loading map data, before entering the game or while changing maps.
They are located inside the GRF in data\texture\À¯ÀúÀÎÅÍÆäÀ̽º (data\texture\유저인터페이스), must be of type JPEG and have to be called loadingXX.jpg where XX is a zero-based index (00, 01, 02...) and limited to about 6-12 files depending on langtype (unless you have diffed Unlimited Loading Screens option).
You should prefer sizes of 4:3 (ex. 800x600, 1024x768) otherwise the loading screen is stretched to fit the screen, which causes certain quality loss. Try to avoid gradients, because the client reduces the amount of colors used inside the image as well.
