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46 votes

Why do we use RGB instead of wavelengths to represent colours?

The goal of the imaging engineer has always been to capture with the camera a faithful image of the outside world and present that image in such a way that the observer sees true to life picture. This ...
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35 votes

Why do we use RGB instead of wavelengths to represent colours?

You said, this is the information that is captured at first by digital cameras. That is not correct. By themselves, sensors on most digital cameras respond to a broad band of frequencies of light, ...
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26 votes
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Why is CMYK more efficient/beneficial than RGB for performing printing operation on white paper?

Both photographic film and photographic digital imaging chips are sensitive to the three light primary colors. In other words, both record components of the image i.e. red, green and blue. ...
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20 votes

Why is CMYK more efficient/beneficial than RGB for performing printing operation on white paper?

Let me debunk one thing: "RGB and CMY are two different color models." They are not, they both form part of one RGB-CMY model. Or probably an RYGCBM model. Ok. That is not entirely true but ...
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18 votes

Can I do "back conversion" of a B&W JPEG to color?

If this image were RAW, the color would still be there. But since it is JPEG, I'm afraid not. The fact that the image is in RGB format does not help, because I'd you look, you will find that in fact ...
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12 votes

Why do we use RGB instead of wavelengths to represent colours?

The reason cameras and displays work in RGB is because our retinas work that way. Since our eyes encode colors with those components (RGB), it is a very convenient system (although certainly not the ...
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11 votes
Accepted

Why do we use RGB instead of wavelengths to represent colours?

I think there are some misconceptions in prior answers, so here's what I think is true. Reference: Noboru Ohta and Alan R. Robertson, Colorimetry: Fundamentals and Applications (2005). A light ...
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11 votes

Why do we use RGB instead of wavelengths to represent colours?

An attempt to answer simply: We cannot practically capture enough information to store a complete breakdown, frequency by frequency, of all the different wavelengths of light present, even just ...
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11 votes

Why is CMYK more efficient/beneficial than RGB for performing printing operation on white paper?

There are two sort of separate issues here. One is RGB vs. CMY. The other is why you add the fourth color, instead of just using CMY (and sometimes, you use half a dozen colors or so, not just four). ...
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10 votes
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Filter for RGB separation and its effect on the image

The spectral response of color filters on Bayer masked sensors closely mimics the response of the three different types of cones in the human retina. In fact, our eyes have more "overlap" between red ...
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10 votes

Why is the screen blend mode named 'screen'?

It's called screen because of the analog process it mimics: From Photoshop Blend Modes Explained : As an analogy, imagine the selected layer and each of the underlying layers as being 35mm slides, ...
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9 votes

Can I do "back conversion" of a B&W JPEG to color?

Unfortunately, a JPEG is a one-way, destructive process. It may be RGB, but it no longer contains the colors originally present, only those written in the B&W conversion process. If you had the ...
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7 votes

Why do we use RGB instead of wavelengths to represent colours?

There are two interacting reasons. Reason (1) is that the eye (usually) receives multiple wavelengths of light from any given point [so to speak]. White light, for instance, is actually [as a rule]...
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7 votes

What are the RGB primaries in a camera?

Digital cameras and films to do not have "primaries". The spectral sensitives of digital cameras and films dictate their response to various wavelengths of light. These native responses are ...
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6 votes
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Can all colors be described with RGB?

Have a look at this introduction to color perception and reproduction. It also contains a comparison of CIE, RGB and CMYK gamuts at the bottom, where CIE represents what the eye can do and RGB and ...
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  • 424
6 votes
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Why do color channels from a digital camera respond slightly to lights of other colors?

There are at least two reasons this happens: There are very few pure (single / narrow frequency band) light sources. That is to say, your red light is not strictly confined to the "red" end ...
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5 votes

Can all colors be described with RGB?

The colors used in a Bayer filter are already centered as closely as possible to the three wavelengths of light to which human eyes are most sensitive. How sensitive each color is relative to the ...
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5 votes
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How to minimise the noise in colour values when moving between colour spaces?

As someone who regularly works in other spaces (most frequently Lab) I'd say not to worry about it. Since your rationale for going to another space is to make changes you're expecting that your RGB ...
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5 votes

Why is CMYK more efficient/beneficial than RGB for performing printing operation on white paper?

While RGB and CMY may be similar, adding K changes things. In theory, CMYK values of (0.3,0.3,0.3,0) and (0,0,0,0.3) should appear as identical grays, but in practice there may be differences which ...
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  • 401
4 votes
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How do I set the RGB values of my monitor to match 6000K for calibration?

Well, if there was a magic RGB setting working for all monitors in the world, there would be no need for calibration anymore, now, would there? In order to bring your display to a given temperature, ...
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4 votes
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Why does Photoshop Curves in 16 bit color depth still use tonal range 0 - 255?

16-bit is only used for internal calculations. What you actually see on your monitor is in 8-bit. Since an 8-bit monitor can only display 256 levels (0-255) and is unable to display the difference ...
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  • 167k
4 votes

color spaces and monitors

Adobe RGB image in a monitor that only displays sRGB? I'm not sure if here lies a misconception. A monitor does not only displays sRGB or Adobe 1998, they display a percentage of them. If a monitor ...
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4 votes

Why is CMYK more efficient/beneficial than RGB for performing printing operation on white paper?

The answer is in your question. It is because TLDR RGB is an additive color model CMYK is a subtractive color model You are using the terms additive color model and subtractive color model without ...
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  • 141
3 votes

How to color correct using known RGB values of a single pixel?

You aren't going to get it exactly right with a single pixel, though you can certainly get that pixel right and then adjust everything else to be visually pleasing (which is usually close enough). To ...
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3 votes

Why do we use RGB instead of wavelengths to represent colours?

The short answer: Because wavelength is a single value, and the entire range of colors we can perceive is not representable by a single value, any more than the dimensions of a rectangular solid can ...
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3 votes

Why do we use RGB instead of wavelengths to represent colours?

tl;dr: It is way much easier to detect light on three broad parts of the spectra than analyse the frequency accurately. Also, the simpler detector means it can be smaller. And third reason: the RGB ...
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  • 1,778
3 votes

Why don't cameras capture using the CIE XYZ color model?

Look at a copy of the chromaticity diagram. Notice that along either the X or Y axis there are no colors. XYZ represents imaginary colors, not real colors. It is impossible to make a XYZ sensor. The ...
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  • 241
3 votes

Why don't cameras capture using the CIE XYZ color model?

Currently XYZ filters are produced using thin film technology. It is not very cheap, and not very suitable for multi-megapixel sensors. It also results in somewhat spiky spectral response curves, ...
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  • 2,001
3 votes

Why do color channels from a digital camera respond slightly to lights of other colors?

Why do color channels from a digital camera respond slightly to lights of other colors? Because the filters placed in front of the silicon on a Bayer masked filter all allow some of all the ...
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  • 167k
3 votes
Accepted

How did color spaces get their names?

I presume RGB is in that order simply because it is the common spectral order — RoyGBiv, in other words. You will sometimes see BRG or otherwise when a particular computer image format happens to ...
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