Uncovering A Problem With The Lumen
Lighting Science
Lighting History
Lighting and Human physiology
100
The photoreceptors in our eyes that allow us to see colors and details in our environment
What are cones?
Cones are responsible for our color vision and are active in bright conditions, while rods can only distinguish between black and white and are active at very low light levels. The range that cones are active is called the photopic range and the range that rods are active is called the scotopic range.
100
Color/wavelength of light that most sea animals can see better than us
What is blue/UV light?
Light between the wavelengths of 450-495 nm travel the furthest in water before being absorbed, making it the most available color of light in the ocean.
100
Thomas Edison invented practical electric lighting in 1879 using this light source technology that eventually modeled the correlated color temperature scale
What is incandescent light?
Edison used a carbon filament (eventually switched to tungsten) and ran so much electric current through it that it heated up until it started to glow. The colors of the glow have been recorded and are used for representing white light to this day.
100
The three different colors of light that the short, medium, and large cone sizes inside the human eye can perceive
What is red, green, and blue?
Due to the fact that our eyes are very good at seeing these colors, we’ve used them as primary colors in all of our screens and denoted a color code based off of having different levels of each of these colors (RGB).
200
Area of our vision comprised of only cones and no rods
What is the fovea?
The fovea is our center of vision and our greatest source of detailed vision.
Because the fovea only has cones, this makes it a great spot to measure photopic vision.
200
This color can rarely flash on the horizon when the sun sets over the ocean
What is green?
The "green flash" appears when shorter blue light scatters away in the atmosphere and red light fails to bend around the ocean, leaving only green light.
200
The latest color of LED invented and a major breakthrough for commercial lighting worldwide
What is the blue LED?
Making a blue LED was a technical challenge for three decades before it was invented in 1993 by Japanese scientists and finally enabled RGB screens.
200
There is no historical evidence behind this, but a popular theory suggests pirates used this iconic accessory to keep their eyes adapted to light and darkness at the same time
What is an eyepatch?
The eye takes about 30 minutes to adapt to dark conditions by using a protein called rhodopsin. While pupils and the retina respond in a coordinated way between the eyes, rhodopsin acts independently, meaning long dark adaptation can be preserved in one eye if it isn't exposed to light.
300
The function that translates radiometric energy into photopic values
-What is V(λ)/luminous efficiency function/photopic luminosity function?
V(λ) was officially adopted by the CIE in 1924, enabling the standardization of the lumen and it's related units.
300
The color you will see on a white surface after you stare at a red surface for a while
(Hint:)
What is cyan?
Our cones "tire out" when we look at something heavily chromatic for a long period of time, leading to vision that temporarily over adjusts to what it's taking in.
300
The year that the CIE color space was officially adopted by the CIE
(This can also be referred to as the chromaticity diagram)
What is 1931?
The CIE 1931 color space is a comprehensive table that includes all possible colors that a human eye can naturally see, and is still respected and used today.
The bright triangle makes up sRGB, and represents the entire body of colors an RGB-illuminated screen can reproduce.
300
Production of this chemical that helps us sleep is blocked by short wavelength (blue) light entering our eyes
What is melatonin?
Melatonin is produced when the human eye isn't receiving signals of blue light, historically from the midday sun. With screens, blue light is easily accessible 24/7. Modern phones have settings that minimize blue light output for those that use screens before bed.
400
The type of cone not present in our center of vision
What is the S cone/blue cone?
Our center of vision is tritanopic. This was observed in 1894 by a German scientist, but was forgotten about it until 1945, when two British scientists independently discovered it and published their findings.
400
The color of the rainbow that's the hardest to distinguish from a white background
What is yellow/greenish yellow?
Because yellow and green are at the center of our luminous efficiency function, we are able to extract more photons from that color and perceive it to be brighter. This is also why red and blue are the easiest to distinguish from a white background.
400
This complex industry standard, backed by IES and spearheaded by Kevin Houser and his former students, was developed over 18 months to combat a lagging CIE-backed color rendering index.
What is TM-30?
TM-30 is a lighting standard meant to supersede the outdated color rendering index. It's meant to predict the quality of color rendering in light sources to a much higher degree than it's predecessor.
400
The direction that peak luminance shifts as human vision goes from photopic to scotopic
(Hint: photopic -> light adaptation, scotopic -> dark adaptation)
What is towards shorter wavelength/blue/left?
Our rod cells have a different peak sensitivity than our cone cells, meaning that the luminosity of all objects change as light levels decrease. Red decreases in luminosity the most, while green and blue retain their luminosity the most. This is called the Purkinje effect.
500
The problem with the lumen
The blue cone is very under-represented in V(λ)
500
A large range of wavelengths removed from light sources in the transition from incandescent light to LEDs
What is infrared light?
Infrared light carries a large amount of heat and uses a large amount of energy. This is why the LED is more efficient and requires less thermal cooling load for buildings. However, recent research suggests that infrared light is very useful for stimulating cell growth, and people sitting inside under LED light deprive themselves of it.
500
The English name of the CIE, which is an abbreviation French name "Commission Internationale de l'Éclairage"
What is the International Commission on Illumination?
500
The reason why looking a few degrees to the side of a star makes it appear brighter to our eyes
What are the traits of scotopic vision?
When viewing a star, incoming light levels are so low that our cones have trouble detecting it and primary brightness perception starts coming from our rods. Since there are no rods in our center of vision, looking a few degrees away will activate more rods and make the star appear brighter.
