4 ms·

"How can something be more opaque than fully opaque?" was my intuition (and probably many other people's). Also RGBA numbers are generally clamped to 0,255.

marcosdumay 5y ago
Ok, I guess the repulsiveness of a clamping operation is something we learn. If one doesn't learn to fear it, it's an operation like any other. Should have been obvious, but I never thought about it.
- Agentlien 5y ago
  Why do you call it repulsive? It's a very common operation in graphics. Even so that certain graphics processors have a flag for floating point operations which allow the results to be saturated (clamped to [0,1]) at no extra cost. I know I prefer to avoid it and design equations so it isn't necessary. That often helps make the math cleaner and more well behaved. But repulsion sounds stronger than what I feel. I would say there are plenty of cases where things do act additively yet we wish to clamp their values to a specific range (often valid colours).
  - marcosdumay 5y ago
    It does appear when you are trying to optimize graphical operations and change the real physical models with approximate ones. It's also a signal that your approximate model won't behave well on repeated application, what is normally not a problem in graphics display, but a red flag on general purpose image processing. On a physical model, it is a very strong signal that you messed something up and your model is wrong. Sometimes you get something that looks like a sigmoid but has the exponential parts very short, so it looks like a clamped linear function, but you normally need some kind of mechanism limiting the output on the linear region. Simple phenomena do not have clamping, it is a very complex operation.
    - Agentlien 5y ago
      Thank you for putting it so well. It seems we're on the same page and I actually agree with everything you said. That's why I avoid it when trying to model things and often see it as a warning flag when reading code written by others.

marcosdumay 5y ago

Ok, I guess the repulsiveness of a clamping operation is something we learn. If one doesn't learn to fear it, it's an operation like any other. Should have been obvious, but I never thought about it.

Agentlien 5y ago
Why do you call it repulsive? It's a very common operation in graphics. Even so that certain graphics processors have a flag for floating point operations which allow the results to be saturated (clamped to [0,1]) at no extra cost. I know I prefer to avoid it and design equations so it isn't necessary. That often helps make the math cleaner and more well behaved. But repulsion sounds stronger than what I feel. I would say there are plenty of cases where things do act additively yet we wish to clamp their values to a specific range (often valid colours).
- marcosdumay 5y ago
  It does appear when you are trying to optimize graphical operations and change the real physical models with approximate ones. It's also a signal that your approximate model won't behave well on repeated application, what is normally not a problem in graphics display, but a red flag on general purpose image processing. On a physical model, it is a very strong signal that you messed something up and your model is wrong. Sometimes you get something that looks like a sigmoid but has the exponential parts very short, so it looks like a clamped linear function, but you normally need some kind of mechanism limiting the output on the linear region. Simple phenomena do not have clamping, it is a very complex operation.
  - Agentlien 5y ago
    Thank you for putting it so well. It seems we're on the same page and I actually agree with everything you said. That's why I avoid it when trying to model things and often see it as a warning flag when reading code written by others.