The ATI1N field is a member of the ImageFormat enumeration in the Sandbox namespace. It represents a specific image format used for texture compression. The ATI1N format is a single-channel compression format, often used for compressing grayscale images or single-channel data such as height maps.

Use the ATI1N format when you need to compress single-channel images efficiently. This format is particularly useful for reducing the memory footprint of textures that do not require color information, such as height maps or other grayscale data.