mister3d

01-29-2009, 05:31 PM

Hi dear friends.

I'm trying to learn some compositing basics, and there's a multiplication operation. To me this means: rgb multiplied is let's say 2.2.2 x 2 = 4.4.4. But why the image becomes darker? If I multiply the image by alpha, it becomes black where the alpha is black and remains the same where alpha is white. Why is that? Isn't 4 is brighter value than 2?

And will addition, subtraction and division do the same weird stuff?

Addition 2.2.2 + 2.2.2 = 4.4.4 brighter

subtraction 2.2.2 - 1.1.1 = 1.1.1 darker

division 4.4.4 / 2 = 2.2.2 darker Right?

I'm trying to learn some compositing basics, and there's a multiplication operation. To me this means: rgb multiplied is let's say 2.2.2 x 2 = 4.4.4. But why the image becomes darker? If I multiply the image by alpha, it becomes black where the alpha is black and remains the same where alpha is white. Why is that? Isn't 4 is brighter value than 2?

And will addition, subtraction and division do the same weird stuff?

Addition 2.2.2 + 2.2.2 = 4.4.4 brighter

subtraction 2.2.2 - 1.1.1 = 1.1.1 darker

division 4.4.4 / 2 = 2.2.2 darker Right?