A tube is an image that has no background in a graphic program. It's an image that is saved as a layer basically. Paintshop Pro has a .tub extension that allows these types of images to be used within it's "tube tool", and applied to various images or backgrounds using that tool at various sizes. It's like a brush tool, but it's loaded with backgroundless images instead of brushes. Any graphic program can make and save backgroundless images (note: this is not a .gif image. A .gif image has a background when opened in a graphic program). While the following aren't technically "tubes" according to the PSP, they are without backgrounds in a graphic program: .psp .pspimage .png The following once you load a mask from an alpha channel, will be backgroundles: .tiff .psd Paintshop Pro will change .psp or .pspimage extensions to .tub, which is the format for using the images from the "tube tool".

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi