On Prussian Blue’s Wikipedia page it says: “Like most high-chroma pigments, Prussian blue cannot be accurately displayed on a computer display.”
What exactly does this mean, and what is it specifically about the pigment that causes this
In: Technology
I wonder if this holds true for “hdr” monitors. They have a larger gamut (“gamut” is the description of what colors a monitor can display).
You can think of it this way, the color of Prussian Blue is a more saturated (‘high-chroma’) blue than the blue that is displayed in your monitors blue pixels. Therefore, the blue pixels alone don’t display the color well. But you also can’t get any help by adding in light from the red and green pixels, since (color-wise) they are pulling you in the opposite direction! The result is that you cannot display the color well on a monitor.
To think about this more completely, it is helpful to look at a chromaticity diagram: https://www.researchgate.net/figure/CIE-1931-xy-chromaticity-diagram_fig4_248392467
If you look at the above chart, you can see that the colors you can make by averaging red, green, and blue, lights are just the ones inside the triangle. Outside the triangle, the color is not represented well. And these outside colors are generally ones that are high in “saturation” or “chroma”, which is defined as a color’s distance from the center of the diagram. Pure wavelengths of light are also “maximum saturation” which is why it is also hard to capture a rainbow’s colors accurately on a monitor.
The way computer screens, our eyes and colour work are all very complicated. Essentially, computer screens emit light at 3 wavelengths (red, green, blue, rgb) and mix them to simulate other colours. This works fairly well for most things, but there are limitations.
Since a computer screen only emits light, other phenomena arent accurately captured. One of these is absorption, which is what prussian blue does. When a pigment does one of these effects, we can simulate its colour with a computer screen, but not the way it interacts with light around it (which actually dictates a lot of how we perceive our vision).
Another (simpler) example is something like vantablack. Since there is no way to simulate black on a computer screen other than turning off the pixels, you cant really tell the difference between something like vantablack or specifically lit black felt. ([https://www.youtube.com/watch?v=Xr1AiExSAnU](https://www.youtube.com/watch?v=Xr1AiExSAnU) is a good 20 minute video if you have the time).
Screens emit too much light to properly showcase the texture and depth of Prussian blue.
Unfortunately, your computer screen is not coated with the special pigment. This means that it cannot correctly display fluorescent colors, because it outputs in RGB (Red, Green, Blue) which cannot clearly represent the hue and brightness that the human eye perceives when examining a fluorescent material.And that’s why fluorescent colors do not appear accurately on computer screens.
https://www.labelvalue.com/blog/label-design/why-fluorescent-colors-dont-work-on-computer-screens/#:~:text=Unfortunately%2C%20your%20computer%20screen%20is,when%20examining%20a%20fluorescent%20material.
Tbf all I did was google why it can’t be done
It’s not really something special about the pigment, as much as it’s about the limitations of your monitor.
Most computer monitors are lcds with a white backlight, and some of that light bleeds through even when a pixel or subpixel is supposed to be displaying black, so with something like prussian blue, there will be more red light coming out of the monitor than would be reflected off the pigment in reality.
There’s also the issue of which wavelengths are the most selective in which type of cones they stimulate, and how tightly your monitor’s color filters select for that one specific wavelength. Basically, you can display yellow by combining red and green, but you can’t make your red more red by mixing in other colors.
If you painted a card with regular blue ink and put it in the sun, it would absorb the red-orange-yellow light and reflect back the blue. Prussian Blue is so intense because it actually takes some of that red-orange-yellow light, then converts it to blue and reflects it back. It appears to be glowing blue.
If you took a photo of the two cards, the Prussian blue wouldn’t look special, because the photo isn’t made with Prussian blue. It’s a similar deal with your monitor, though in that case they’re both glowing. Even the ink card is giving off light, because it’s really a glowing image on a monitor, rather than absorbing light as it does in the real world.
It’s a bit like laundry detergent with optical brighteners. They contain a fluorescent agent which converts some invisible ultraviolet light to visible light. This is why so many laundry detergents glow like crazy under a black light. Much of the light given off by a UV black light is in the invisible spectrum; a fancy one will emit very little visible light. A white towel that has never been washed with optical brighteners will be hard to see. Wash it with optical brighteners and it will glow blue. In the sun, it will look brighter too. why fluorescent-died stuff seems brighter than it should.
The range of colors our eyes can perceive is not the exact same range of colors a digital output can create. It’s close but things like this are out there to remind us digital images are interpretations of light- not the light itself.
A computer screen works by changing the brightness of lots of red, green and blue lights (subpixels). That means it’s limited to the colors of those lights. You can’t display anything more blue than the blue pixels, more red than the red pixels, or more black than turning the pixels off.
Google a picture of a mirror and try to see your reflection. It doesn’t work. Some colors can’t be replicated my a screen.
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