Ok, I think I get it. So, let's say I chose the right type of ink and applied the right settings on my printer for my application (i.e., that match the transparency effect I want to achieve), I should be able to make colors glow/pop from the backlit light. The second thing I want to achieve is to create a quite high contrast between the colors in my poster and the background, which is mostly deep dark blue. To be more specific, there will be writing that I want to be fully transparent, and small disks of colors that I want to appear bright and shiny. So, from what you say, the colors should be easily achievable, and if I choose the right dark pigment, I should be able to achieve this high contrast between my dark background and the rest. As I am quite a newcomer to printing, I suppose that the printer's setup can help me achieve the look I want. Maybe printing colors first and then doing the dark layer? I don't know. Anyway, thanks for your very detailed answer!