Prepare the images as animation frames
Start with individual PNG or JPEG images rather than a video or an animated image container. PNG is usually useful when the artwork needs transparency; JPEG has no alpha channel and is decoded as an opaque image. The tool does not split GIF or animated PNG files into frames, and it does not resize source artwork during packing.
Choose a consistent naming convention before importing. Natural filename order is useful for names such as walk_01 and walk_02, while selection order retains the order supplied by the file picker. You can inspect and change the animation sequence in the workspace. Duplicate names receive a distinct suffix so one frame does not silently replace another in the named-frame JSON.
Inspect the image and the data together
After packing, the atlas view shows where each physical rectangle sits. Optional outlines distinguish frame pixels from the larger padded allocation. These outlines are only a preview overlay and are not drawn into the downloadable PNG. Use the frame menu when a small rectangle is difficult to select directly.
The animation preview reconstructs frames from the packed image. It applies the stored rotation and places a trimmed frame back inside its original dimensions. This makes it a useful check of the image and coordinates together. It still cannot substitute for testing your actual engine, texture sampler and camera settings.
Keep the export files as one result
Download atlas.png with atlas.json from the same prepared result. Repacking can change every coordinate, so a JSON file from an older atlas should not be reused with a newer image. The detailed manifest records physical rectangles, original dimensions, trim offsets and frame order for inspection or a custom importer.
The loading notes target specific Phaser and PixiJS conventions rather than promising every engine format. Use the exported animation order and FPS when creating the animation. Keep the source images as well: the atlas is a useful delivery asset, but it is not an editable replacement for the original layered artwork or source animation project.