The Lightflow Texture Format is an image format
specifically designed to manage 3D texture data within the
Lightflow Rendering Tools.
In particular this format has three channels: a color
channel, an alpha channel, and notably a depth
channel.
All of these channels are optional, that is to say there may be
an image containing only one or two of them (for example the
color and the alpha channels).
As regards the first two channels, there is nothing to say,
because they are present in almost all the image formats.
On the contrary the depth channel is peculiar to this format,
since it is used to store the depth of each pixel of the image.
This type of information is usually generated by a rendering
process, but may also be generated procedurally, for example to
model an height field.