Hello, I'm one of the developers of Pheon. Please contact our technical support at
support@apago.com and we will be happy to answer any questions.
The reason Pheon uses indexed CMYK images is they are 1/4 the size of a raw CMYK image. Using lossless compression such as LZW or Flate would only get 2:1 compression. The LW, not CT, layer is tiled to reduce the memory requirements in the RIP. Tiles also allow Pheon to optimize the image format (raw, compressed, indexed, etc) and colorspace (DeviceGray, DeviceCMYK, Separation or DeviceN) used per tile.
Sincerely,
Dwight Kelly