You probably have never considered the actual quality of white light before as until LED lighting came along we didn’t need to as our usual lighting did the job well enough. We have always understood that different colors of light will of course affect how we see things, but normal light from lamps is just white light – right?
In a hurry? The Quick & Easy Summary to CRI: The colors of our world are recreated by the quality of the light that illuminates them. How well artificial lighting does this is measured by a CRI test and you should use lighting with as high a CRI value as possible and do not go under 80CRI.
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For all the incredible advantages that LED lighting brings to our spaces, one detail that has struggled is how the colors of our environment are reflected back to us, or in other words how they are rendered. This is an important detail to understand as after all, what we all see is only as good as the light that is shining on it.
So follow our quick and easy to understand guide on the essentials of what you need to know about LED Color Rendering, so you can choose your lighting in confidence.
Don’t mistake color rendering with color temperatures: How to Choose LED Color Temperatures
It would be good not to have to bother talking about how good the artificial light we create actually is and leave all the techy bits to the manufacturers but as the LED and fluorescent light sources we use do not all offer the perfect rendering of colors, we are left with some choices to make.
You will see the term CRI on lighting packaging and specifications, which is the abbreviation for Color Rendering Index. The color rendering index is the measurement of how well colors are reproduced on objects by an artificial light source compared to the natural white light from the sun or daylight.
Daylight is the benchmark of true lighting as it recreates colors in objects perfectly by carrying the full visible spectrum; it’s made up of a soup of colors that when combined look white to our eyes and importantly contains everything it needs to truly render colors.
CRI is very important in lighting as we need to know just how well the colors in our interior on fabrics, furniture, objects and indeed people will look when lit by our chosen source of light.
The Color rendering index is reported by a numerical scale of 0 to 100, so it’s as easy to understand as a percentage is – with 100 being perfect.
This index score is the average result of how well the light source represents a test palette of 8 basic pastel colors reported in a score of Ra. The higher the Ra score the truer all colors are meant to be but by today’s standards that’s too simplified. Six more colors have been added to the CRI test for a broader representation of colors in the score but it’s still far from perfect and not all manufacturer’s do that.
So the CRI score is not faultless and unhelpfully comparisons between products can be misleading as not the same test is carried out on all products but it gives a good indication of what we are using.
The best CRI values are the highest ones you can find and our advice is buy as good as you can afford. However, in practise unless the CRI of a light source is really bad ie under 80CRI, you are not really going to notice what is happening to your colors … unless you compare them with a higher CRI source and then you will be amazed!
Standard LED light sources have always struggled to reproduce the color red regardless of whether they have a high or low CRI score and has historically not been reported in the standard 8 color CRI test.
The best CRI light sources produce a high R9 score indicating a truer representation of the fundamental red’s we find in so much of life. Look out for manufacturer’s who report on their light source’s R9 swatch test and make sure it has a score of at least 80.
The best CRI values are particularly recommended for lighting artwork and for spaces where you have invested time in getting the interior colors right.
Commonly in LED lighting the two main types of Color Rendering Index score are 80CRI and 90 CRI with manufacturer’s offering their premium sources at possibly 95CRI or 98CRI. If it’s 80CRI vs 90CRI, then choose 90CRI everytime which actually has become the new common standard.
For many years 80CRI was the standard for all decent LED lighting. 80CRI represents colors at an average of 80% to their true color when tested against daylight and in practise this works perfectly well. However, do so in the knowledge that if you choose 90CRI the light will look cleaner and on some lighter colors actually look brighter even though the lumen output is the same.
The Temperature of a color is the value given to the color of white light so you understand how warm or cool it is – not how well that color of white light will create other colors when it illuminates them.
You can have the same color temperature but with different CRI values as the quality of representation of colors on objects is not dependent on the originating color of light but how that color is mixed. It’s a little like paint, you can mix paint colors in a variety of ways to get to the same color and it’s the same with light. The difference with light is the combinations of colors affect what we see.
CRI as a test was developed in the 1930’s and with just the 8 samples of color to score by modern LED lighting has not been quantified properly with such a blunt metric.
In 2015 the CRI test had a successor in the catchy named TM-30-15 evaluation. To make a long explanation short – color rendering now has a test that is an average of 99 sample colors, breaking the results down into two quantifiable metrics that frankly only lighting geeks really know what they mean. It’s no surprise that the longstanding CRI measurement has remained the common term of reference in more retail focused product specifications for the casual user.
The Best LED Light color rendering for the pages of a book should be as high as possible. The acceptable LED color rendering value is 80Ra or 80CRI or more. A higher CRI value will seem to feel brighter.
The Best LED Light color temperature is 4000K for a crisper brighter feel and for the harder of sight, with 3000K as a comfortable practical warm white to have at a bedside to read by.
The Best LED Light level of illumination for reading is barely different by choice of white light color with the cooler whites more efficient creating a little more light for the power used.
The ability to read a book is actually more to do with the level of illumination – we recommend between 100 – 200 lumens in output as a comfortable level from a dedicated LED reading light.
If the choice is between LED or fluorescent light sources on the basis of which one has the highest CRI value, then commonly LED lighting is the better choice. The CRI for fluorescent bulbs at the budget end start at around 50Ra whereas basic LED lighting has a CRI of 80 upwards, Higher quality fluorescent can reach a score of 98Ra as can LED.
LED bulbs or officially termed LED Lamps are given a CRI metric so we know how well the light is makes will recreate the colors of the objects and interior it is used in. Your choice of LED bulb should be no less than 80Ra or 80CRI.
LED bulbs and LED lamps that have a CRI test score of 95Ra and above and check that they are creating richer reds. Check that the R9 score from the wider CRI test is at least 90.
Ra is the metric for the scoring of the colour rendering index, with which the quality of color reproduction from lamps and lighting is described. The higher the Ra value is towards a score of 100, the greater the true representation of color on objects from an artificial light source.