Geoffrey wrote:
Olivier Ripoll wrote:

You misunderstood. A portion of the "value" (RGBA) of the pixel is selected, not a portion of the pixel geometry. Think of it like a phantom (ghost, whatever you call it): The shape of the human body is totally preserved, but you can see through it.

Still, I didn't know you could have a partially transparent pixel. I thought transparency was at the pixel level, that is either a pixel was transparent, or it was not. Then again, I've a coder, not an artist or image expert.

Well, think as a human being (not a coder, nor an artist). What do you call transparent in life ? The windows of your house or office, be they perfectly clean, dirty or tainted are "transparent". You feel intuitively that transparency is not a binary property, it is a continuum of states. You would never qualified a door opening of "opaque" and "transparent", but you use "open" and "closed".

Said with other words, transparency is the property of an object that is present. You do not say of an object that is absent that it is tansparent, you say it is not there.

This is why transparency is by definition a gradual property. The use of transparency for a binary property is due to the limitations of a very popular and now outdated graphic format (gif). But outside the world of computer graphics,the word transparent has kept its original meaning.

To end with, I would just mention that some people often make the confusion between transparent and translucent. Transparency lets you see and image through. Translucency lets you only see light through, like a fog, a cloud (not too thick), curtains.



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