Post subject: The real color of a pixel on a computer screen
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Hello! I'm posting this here, since two of my friends don't stop arguing and I'm somewhat interested in this debate! One says that the smallest pixel on the screen is only blue, yellow or red, the three primary color. His reasoning is that, since a computer screen is like 1024 X 768 thingy, that means there is more than 700 000 pixel to color. And if we assign a different color to each pixel, the amount of information is huge. Why don't we see only in blue, yellow or red on a screen? it's because the pixel are so small the eyes can't distinguish it. With yellow and blue (50% 50% for example), in a certain region, we should see green. etc. One says that, sionce we can color green on a single pixel with GIMP or photofiltre, a pixel is not necessarily only red, yellow and blue. Anyone experienced can answer me?
Lex
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http://en.wikipedia.org/wiki/Pixel I'm not sure where you're getting "yellow" from. The primary colors of light are red, green, and blue.
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So, it's with blue, red and green? EDIT: I didn't see the wikipedia page before posting, my bad. Thank you! So, it's the subpixel that are red, green and blue and not the pixels?
Lex
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Yes. Colors displayed on LCD monitors are comprised of varying levels of red, green, and blue.
Post subject: Re: The real color of a pixel on a computer screen
Noxxa
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niamek wrote:
His reasoning is that, since a computer screen is like 1024 X 768 thingy, that means there is more than 700 000 pixel to color. And if we assign a different color to each pixel, the amount of information is huge.
Assuming 24-bit colors, you can fit the color information of a pixel in 3 bytes. 3 bytes * (1024 * 768) = 2359296 bytes = ~2.36 MB. The amount of information isn't that crazy.
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I'm confused: it's the subpixels or pixels that are in red , green and blue?
Lex
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1 pixel on your LCD is comprised of 3 subpixels: 1 of each primary color.
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Good, so it's the subpixel that are blue, red and green! Thank you. :)
Editor
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Fun fact: people can tell when individual subpixels are "wrong". Try viewing text anti aliased on a subpixel level with the wrong subpixel order.
Post subject: Re: The real color of a pixel on a computer screen
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niamek wrote:
One says that the smallest pixel on the screen is only blue, yellow or red, the three primary color. His reasoning is that, since a computer screen is like 1024 X 768 thingy, that means there is more than 700 000 pixel to color. And if we assign a different color to each pixel, the amount of information is huge. Why don't we see only in blue, yellow or red on a screen? it's because the pixel are so small the eyes can't distinguish it. With yellow and blue (50% 50% for example), in a certain region, we should see green. etc. One says that, sionce we can color green on a single pixel with GIMP or photofiltre, a pixel is not necessarily only red, yellow and blue.
Good, so it's the subpixel that are blue, red and green!
Ok, I may be a bit obtuse here, but I have hard time understanding what exactly the issue is about (or how that was the answer to said issue). "His reasoning is that ... if we assign a different color to each pixel, the amount of information is huge." I'm not sure I understand what the issue is here, or how the "pixels are divided into subpixel" answer helps it in any way. "Why don't we see only in blue, yellow or red on a screen?" I don't understand what the problem you are envisioning is (or even what this question is actually asking). Could you please elaborate? "One says that, sionce we can color green on a single pixel with GIMP or photofiltre, a pixel is not necessarily only red, yellow and blue." Again, I don't really understand what the argument here is. (I know that the question has already been (apparently) answered. It just bothers me that I can't make head or tails of it.)
Tub
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Lex wrote:
The primary colors of light are red, green, and blue.
Just to clarify, there's nothing too special about these "primary" colors from a physical perspective. These three colors were chosen because they correspond well to the three types of color-detecting photoreceptor cells (cones) in our eyes. By sending light at these three wavelengths, the three types of cones can be triggered individually, thus recreating most colors perceivable by humans. There are animals with different color vision than ours, and many of those can easily distinguish between a picture on a monitor and the real thing.
m00
Post subject: Re: The real color of a pixel on a computer screen
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Warp wrote:
niamek wrote:
One says that the smallest pixel on the screen is only blue, yellow or red, the three primary color. His reasoning is that, since a computer screen is like 1024 X 768 thingy, that means there is more than 700 000 pixel to color. And if we assign a different color to each pixel, the amount of information is huge. Why don't we see only in blue, yellow or red on a screen? it's because the pixel are so small the eyes can't distinguish it. With yellow and blue (50% 50% for example), in a certain region, we should see green. etc. One says that, sionce we can color green on a single pixel with GIMP or photofiltre, a pixel is not necessarily only red, yellow and blue.
Good, so it's the subpixel that are blue, red and green!
Ok, I may be a bit obtuse here, but I have hard time understanding what exactly the issue is about (or how that was the answer to said issue). "His reasoning is that ... if we assign a different color to each pixel, the amount of information is huge." I'm not sure I understand what the issue is here, or how the "pixels are divided into subpixel" answer helps it in any way. There is an infinite amount of color we can generate. So, it would be hard to a computer to be able to remember all those different color, then color the right pixel with the right color... And to color the entire screen with different color. It was simpler to color just with three color than with an incredible amount of color. We aren't experienced in the domain, logic just made the argument... He didn't know about the subpixel apparently, since we thought that a pixel were the smallest thing on a computer screen. "Why don't we see only in blue, yellow or red on a screen?" I don't understand what the problem you are envisioning is (or even what this question is actually asking). Could you please elaborate? It was a question followed with an answer. My friend that said that a pixel is made of blue red and green. Then, why can we see pink in a square of 4x4 for example? it's because there is like 50% red and 50% blue in that small section of the screen. Since they are small, our eyes can't dissociate the two colors, they "fuse" them into a single color. Something like that. "One says that, sionce we can color green on a single pixel with GIMP or photofiltre, a pixel is not necessarily only red, yellow and blue." Again, I don't really understand what the argument here is. It's basically just this: open an application such as GIMP, photoshop, etc. Open a new file 1x1 pixel. Zoom the pixel so you can see the big square. And see if you can color with other color than the primary color. Since we can do that, a single pixel is not composed of only blue, red and green. (I know that the question has already been (apparently) answered. It just bothers me that I can't make head or tails of it.)
I hope I answered your questions.
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Not really, but I suppose it doesn't matter. It's not like it's something of great importance to understand.
Post subject: Re: The real color of a pixel on a computer screen
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niamek wrote:
There is an infinite amount of color we can generate.
Everything is finite, including colours.
niamek wrote:
So, it would be hard to a computer to be able to remember all those different color, then color the right pixel with the right color... And to color the entire screen with different color.
As noted, that is not true. Take a resolution of 8K, the highest resolution available today. That is 8 million pixels where each pixel takes 3 bytes. That is 24 million bytes, or roughly 23 MB. Hard to remember? Hardly when systems have GB of memory today!
niamek wrote:
It was simpler to color just with three color than with an incredible amount of color.
No. Take 3 colours of 1 byte each and you need to 3 bytes to store all information. You can thereby create up to 16 million colours. But then again, we could also store 16 million colours by giving each colour a unique value and store them in 3 bytes. Same thing. Same storage. No difference. But of course, you are right in that it's infeasible to use a million different colours inside a monitor or TV.
niamek wrote:
It's basically just this: open an application such as GIMP, photoshop, etc. Open a new file 1x1 pixel. Zoom the pixel so you can see the big square. And see if you can color with other color than the primary color. Since we can do that, a single pixel is not composed of only blue, red and green.
This seems like you did the argument backwards. Assuming that you could zoom onto a single pixel (which you cannot, btw), if you can then colour that pixel with any colour, then the pixel cannot only consists of one colour: red, green or blue. It must consist of all three to create the desired colour. You cannot zoom into a single pixel because what you get is a "logical" pixel and not a "physical" pixel. A logical pixel is basically the smallest possible element in an image, but since it's larger then a physical pixel, it must consists of many physical pixels. You cannot take a physical pixel on your monitor/TV and enlarge it. It's a physical thing.