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Old 11 July 2018, 15:29   #41
ajk
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Transparency in this context has to do with how much will show through if you have two images on top of each other. So it does not directly affect the brightness, rather how much or little the colour covers what it is on top of.



There are also computer architecture / memory alignment related reasons to use a 32 bit value to represent a pixel, rather than 24 bits, even if transparency isn't particularly needed.
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Old 11 July 2018, 19:37   #42
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Originally Posted by BullyDog View Post
That's what I thought is luminosity but instead we call it transparency. The RGB goes from dark to bright like dark red to pink for R. Transparency are what add brightness to the color.

I have that correct?
No.

If R,G and B are all set to 0 then it is black. If they are all set to 255 then it is white. It really is as simple as that.

With OpenGL, 0 is absolute minimum and 1 is absolute maximum (this allows fractions to determine what the level is, which works with any bit depth, be it 4-bit, 8-bit or even 12-bit for the R, G and B levels).

Transparency is more for overlays, be it on a genlock (for a caption or logo on a TV broadcast display) or for OpenGL texture mixing for shaders. If the alpha (transparency level) is set to 0, then it is fully transparent and technically invisible, and if it is set to 1, then it is fully visible and fully opaque. (The 0 and 1 might be the other way around, but that's how I understand it).

This is all highly technical, but there's plenty of information out there for people who are interested.

EDIT: Ajk, you've summarised it better than I ever could. I was lacking a visual example.
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Old 11 July 2018, 20:44   #43
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I guess it's back to classes for me boys.
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Old 12 July 2018, 07:36   #44
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I really hate it when I hear people say, "Why isn't a kilobyte just 1000 bytes instead of 1024? That's stupid!" That's because computers work on a principle of Base 2, not Base 10. It's really, really simple.
Sure, but what has that got to do with anything discussed here?
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Old 12 July 2018, 10:06   #45
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I really hate it when I hear people say, "Why isn't a kilobyte just 1000 bytes instead of 1024? That's stupid!" That's because computers work on a principle of Base 2, not Base 10. It's really, really simple.
Try telling that to hard drive manufacturers.
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Old 12 July 2018, 10:27   #46
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Ajk brought it up, not me.
No he didn't, he talked about memory alignment, your comment had nothing to do with that.

EDIT: but yeah, let's not go off topic
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