The DXT3 field is a member of the ImageFormat enumeration in the Sandbox namespace. It represents a specific image format used for texture compression. DXT3 is a block compression format that provides a balance between image quality and file size, supporting explicit alpha channels. This format is particularly useful for textures that require alpha transparency with moderate quality.

Use the DXT3 format when you need to compress textures with alpha transparency, and when the quality of the alpha channel is important. This format is suitable for scenarios where you need a good balance between compression and visual fidelity.