Opague/Transparent/translucent

[maverick_pol]

Hi guys,

Some time ago I came across this site:
http://answers.yahoo.com/question/index?qid=20080207053738AAnOr2S

and I want to ask for definitions of these 3 : OPAQUE,TRANSPARENT,TRANSLUCENT.
and I especially ask if anyone could explain the difference between
transparent vs translucent.
I more less understand the idea, but would like to here a guru giving some examples from QT.

I will really be thankful.

[Brandybuck]

Opaque means there is no alpha channel (or max alpha value), you can't see anything at all under the widget. Example would be QColor(0, 0, 0, 255).

Transparent and translucent mean almost the same thing, there is an alpha channel and you can see what is behind the widget. An example would be QColor(0, 0, 0, 127). But "translucent" also implies a diffusion effect. For example, glass is transparent but frosted glass is translucent. For computer graphics you need to do more than just combine two images through an alpha channel, you also need to apply a filter of some sort (usually a gaussian blur).