Lighting is an indispensable part of our daily lives. However, not only the brightness of the light, but also how it reflects colors is of great importance. This is where the Color Rendering Index (CRI) comes into play. If you want to examine this lighting element in detail, you can take a look at our content called “What is Color Rendering Index (CRI)?”. We wish you pleasant reading and a good day.
CRI (Color Rendering Index) is a unit of measurement that indicates how accurately and naturally a light source renders colors. Although this unit of measurement has a scale between 0 and 100, the closer the CRI value is to 100, the more natural and accurate the light source shows the colors of objects. In this context, if the CRI of a light source is above 80, this usually means that it offers good color rendering and is sufficient for indoor lighting. CRI values of 90 and above are preferred in professional photography, art galleries, textile production and healthcare. Because color accuracy is of great importance in these fields. On the other hand, lighting with low CRI values (e.g. CRI < 70) can make colors look pale, artificial and inaccurate. This is undesirable in retail spaces and design-oriented spaces. As a result, light sources with a CRI value provide excellent color accuracy along with energy efficiency.
CRI (Color Rendering Index) has a scale between 0 and 100 and determines how accurately light reflects the true colors of objects. At this point, CRI values are divided into three main categories. These are; low CRI (0-60), medium CRI (60-80) and high CRI (80-100). Light sources with a CRI of 60 and below can make colors look quite distorted and artificial. For this reason, this type of lighting is mostly used in industrial or security lighting.
Although lights with a CRI between 60-80 reflect colors relatively accurately, they are not sufficient for sensitive visual applications and are generally preferred for commercial or general indoor lighting. In addition, CRI values in the range of CRI 80-90 are suitable for indoor or office lighting. Finally, lights with a CRI of 90 and above are preferred for professional applications that require high color accuracy, such as art galleries, museums, photography studios, hospitals and textile production.
CRI scales are divided into 8 different categories. These generally calculate how accurately the colors are reflected by the light source. At this point, the ranges of the CRI scale are listed as follows;
R1, usually a mixture of light gray and red, is one of the main criteria for determining the overall color accuracy of light. Since this color is also associated with the tones of human skin, it is especially preferred in make-up lighting, beauty salons and photography studios. Accordingly, light sources with high CRI values reflect the R1 value accurately, making skin tones look natural and healthy, while low CRI lights can make colors look pale or lifeless.
R2 is a light range that determines how accurately the light source reflects yellow-green tones. This range plays an important role in plant foliage, landscapes and interior decoration in general. This is because a correctly chosen R2 value helps to make green tones look vibrant and realistic, so that plants look more alive. However, lights with a low R2 value will make the green tones found in nature and plants look washed out or artificial, which is a negative for landscape lighting and greenhouses.
The R3 value is a measurement that determines how well the light can show yellow colors. This measurement is important for creating a warm and inviting atmosphere in indoor lighting. A high R3 value is preferred especially in restaurants, hotels and indoor lighting. In this context, light sources with low CRI values make yellow appear duller or greenish, causing the environment to lose its natural and warm atmosphere.
R4 measures the ability of light to accurately reflect shades of green. This color scale is one of the most widely used colors in nature and interior decorations. It is especially important for gardens, office plants, landscape lighting and sports fields. In this context, lights with a low R4 value can reflect green in a faded or artificial way, making it look unnatural.
R5 refers to how accurately light can show shades of sky blue. This color is an important factor affecting the natural appearance of the sky and water. A high R5 value is especially necessary for pool lighting, aquariums, beachside and outdoor lighting. Lights with a low R5 value can make blue look pale or grayish. This can prevent the water or sky from looking vibrant and natural.
R6 is a range that determines how light reflects shades of violet. This range is often used in decorative lighting, artistic spaces and special design projects. Thus, the right R6 value makes the color purple appear rich and deep, while light sources with a low R6 value can make purple appear bluish or lifeless. This is a negative situation for art galleries and jewelry stores where color accuracy is important.
R7 measures how accurately light can show shades of light blue. Light blue is a color commonly seen in natural elements such as sky, sea and ice. A high R7 value is required especially for tourist attractions, underwater lighting, maritime lighting and poolsides. Light sources with low R7 can make light blue appear white or washed out, reducing the aesthetic quality of the environment.
In order to get detailed information about the importance of the CRI value, it should be considered in 4 different categories. These are; Measuring the Quality of Artificial White Light Sources, Measuring the Reflected Color of an Object under Artificial Lighting, Providing Accurate Color Representation and Providing Visual Comfort and Efficiency. To discuss these topics in detail;
CRI (Color Rendering Index) is one of the most important criteria determining how accurately artificial white light sources reflect colors. This criterion reflects different light sources such as LED, fluorescent and halogen lamps in different ways. In this context, a light source with a low CRI value can make colors look faded, artificial or different, while a light source with a high CRI value reflects objects as close to daylight as possible. Therefore, the quality of light makes a big difference, especially in areas such as retail stores, museums, photography and interior decoration.
CRI measures color accuracy by comparing the colors of an object under natural light with the colors that appear under artificial light. Especially in the fashion, textile and automotive industries, the color accuracy of products is of great importance. For example, store lighting with a low CRI can cause clothes or products to appear differently in shop windows, which can create a negative shopping experience for consumers. Light sources with high CRI minimize such errors by making colors look realistic and consistent.
A high CRI ensures that objects can show their true colors without altering them. Especially in environments such as art galleries, restaurants and hotels, the correct perception of colors directly affects the atmosphere of the space and the customer experience. In food presentations, make-up applications and healthcare, color fidelity is a critical factor. For example, in hospitals, skin tones and the colors of medical equipment must be perceived accurately for accurate diagnosis. Lights with low CRI can cause misperceptions and put safety at risk.
Light sources with a high CRI value are less tiring on the eyes and provide a more comfortable visual experience for long-term use. Especially in offices, educational institutions and workspaces, accurate color rendering reduces distraction and increases productivity. Low CRI lights make it difficult for the eye to perceive colors, which can lead to eye strain, headaches and low concentration. High CRI also makes workspaces more comfortable and provides a healthier lighting environment for people.
As a result, CRI value is a critical factor that determines the quality and color accuracy of light, while accurate color rendering provides better visual perception, efficiency and comfort in many areas from daily life to professional use. Therefore, paying attention to the CRI value when choosing lighting creates a better quality and healthier lighting environment in the long run.
There are 2 different methods of measuring the color rendering index. The first one is measuring the CRI of daylight and the other one is measuring the CRI of lights other than daylight. In this context, it is necessary to consider in detail;
Daylight is considered the reference point on the CRI (Color Rendering Index) scale and has a CRI of 100. The CRI measurement of daylight is therefore usually done with a spectrophotometer or colorimeter. This analyzes how it spreads across the entire spectrum and how it contains different wavelengths. In addition, in areas that require precise color accuracy, such as photography, art galleries and medical diagnostics, the CRI of daylight is used as a reference.
The CRI of artificial light sources used outside daylight is measured to determine how accurately the light reflects colors on objects compared to daylight. As a result, when measuring the CRI value, the color reflection of an object exposed to the light source is evaluated by spectral analysis and compared with how it looks under daylight. Thus, CRI measurement of artificial lights is of great importance in areas where color accuracy is critical, such as shops, hospitals, offices, art galleries and production facilities.
There are 5 main factors that affect CRI scores. These factors are generally as follows;
The type of light source is one of the most important factors directly affecting the CRI (Color Rendering Index) score. This factor directly affects the CRI value by determining the spectral distribution of light, color accuracy and reflection on objects. For example, incandescent and halogen lamps offer CRI values close to 100, while fluorescent and some LED lamps may lack certain colors and lower the CRI. In addition, full spectrum LEDs and lighting with a spectrum closest to daylight offer the highest CRI values.
The material of the illuminated object has a major influence on the absorption and reflection of light. This effect changes the CRI (Color Rendering Index) score depending on the object's surface characteristics, texture and how its color is perceived. Thus, reflective materials such as metal surfaces and glass can change the spectrum of light, while matte surfaces such as fabric and wood can reflect light more accurately, improving color accuracy. Therefore, the surface structure of the object and how it reflects light should be taken into account when evaluating the CRI.
The distance between the light source and the illuminated object and the angle of incidence also affect the perception of CRI. Therefore, light coming from a close distance and directly reflects the colors of the object more accurately, while light coming from a long distance or at an oblique angle can cause distortions in the spectrum. It is also important for the width and distribution of the light source.
Since the CRI score measures the color accuracy of light on objects, the color structure of the object is also an important factor. Some light sources render certain colors more accurately, while others may distort or miss some hues. In particular, the accurate projection of colors such as R9 (saturated red) is a critical factor that determines the actual quality of the CRI. For example, lights with a low CRI can make reds appear more orange or washed out. This can lead to unrealistic color rendering in rooms and art spaces.
Finally, the physical structure of the lighting environment can directly affect the CRI value. For example, an environment with white or light-colored walls can improve CRI perception by reflecting light more naturally, while dark or glossy surfaces can alter the light spectrum. Also, additional light sources in the environment (a combination of lights with different color temperatures) can affect how colors appear and change the CRI accuracy.
CRI (Color Rendering Index) has a direct impact on human perception. This is mainly because it determines how we see and feel colors and how we perceive the objects around us. Thus, high CRI lights can make the colors of objects appear natural and lifelike, while low CRI lights can distort visual perception by projecting colors in a faded, lifeless or inaccurate tone. For example, in a low CRI environment, shades of red may appear pale or brownish, while human skin may appear unhealthy or sickly. This can have negative consequences, especially in areas where color accuracy is important, such as makeup applications, healthcare, retail stores and restaurants.
In addition, low CRI lighting can cause eye fatigue, lack of concentration and headaches. This is because the human eye spends more effort to perceive the right colors. As a result, the natural and accurate perception of colors has a positive impact not only on aesthetics, but also on human psychology and mood.
CRI is traditionally a method of measuring how closely a light source reflects colors to daylight. However, CRI has some limitations, so the Color Quality Scale (CQS) was developed. CQS measures light quality more accurately by using a wider range of colors (15 colors) to overcome the shortcomings of CRI. In this context, CRI does not take into account some critical colors, especially saturated red (R9), whereas CQS evaluates these colors as well, providing more reliable results. Furthermore, CQS is preferred for measuring color accuracy, especially in the retail, art and film industries, as it provides a model that better reflects color saturation and human perception. In summary, CQS offers a more comprehensive assessment of color accuracy by performing a broader color analysis compared to CRI.
TM-30 is a more comprehensive color measurement method developed to address the shortcomings of CRI in modern lighting technologies. Using 99 different reference colors, this method analyzes in much more detail how light sources reflect colors. Thus, situations where CRI is deficient in certain colors (especially red, blue and saturated colors) can be evaluated more accurately with TM-30. To summarize, TM-30 is a more modern, detailed and reliable color measurement standard than CRI and provides more accurate results, especially in new generation lighting technologies such as LED.
Finally, GAI is another measurement method developed to address the shortcomings of CRI and focuses on determining the color saturation of light. Whereas CRI only assesses the accuracy of colors, GAI measures how vibrant and rich those colors look. This is why some lights with high CRI can make colors look very natural, but keep color saturation low, weakening visual perception. This is where GAI comes in and helps identify light sources that make colors appear more vibrant and saturated.
With the development of lighting technology, more natural, efficient and human-oriented solutions in the field of color rendering (CRI) will come to the fore in the future. In this context, new generation full spectrum LEDs aim to provide the closest color accuracy to daylight by offering much higher CRI values compared to traditional light sources. In particular, improved phosphor coatings and spectral optimization techniques are used to better reflect R9 (saturated red) and other saturated colors. In addition, Smart Lighting Systems and Human Centric Lighting (HCL) concepts aim to integrate the changing spectral characteristics of daylight at different hours into artificial lighting to create light environments that are more natural and compatible with our biological clock. In this way, dynamic lighting solutions that support human health and productivity will become widespread in living spaces such as offices, hospitals, schools and homes. At the same time, within the scope of sustainability-oriented studies, energy efficient and environmentally friendly LED technologies with high CRI will become the standard in the lighting industry in the future by reducing the carbon footprint.
In short, in the future, color rendering technology will not only improve color accuracy, but will also evolve in an integrated manner with solutions focused on protecting human health, productivity and the environment
R9 is a CRI (Color Rendering Index) component that measures how accurately saturated red color is projected. Most artificial light sources reflect the basic R1-R8 colors well, but can perform poorly at R9 (saturated red). This is particularly common in some modern lighting such as LED and fluorescent lights. A low R9 value can cause red hues to appear washed out, brownish or close to orange. This problem can negatively impact visual perception in industries where color accuracy is critical, such as food, healthcare and fashion.
R9, which is of great importance in restaurants to make food look delicious and appetizing, makes most foods such as meat, tomatoes, peppers and fruits look vibrant. For this reason, lighting with a low R9 value can make these foods look paler and less appetizing, while lights with a high R9 value reflect red tones accurately, making food look fresh and attractive. Therefore, high CRI and high R9 lighting should be preferred in restaurants and cafes.
In hospitals and health centers, the correct perception of colors is of vital importance. It therefore helps doctors and healthcare professionals to accurately assess skin tones, wounds or blood vessels when making a diagnosis. Lights with a low R9 value can cause skin color to appear pale or abnormal, which can lead to misdiagnosis. Light sources with high CRI and high R9 are essential, especially in operating rooms, intensive care units and laboratories. This improves the safety of sensitive medical procedures and increases the likelihood of accurate diagnoses.
Daylight (natural sunlight) is the light with the best CRI and is considered to have a CRI of 100. Among ordinary light sources, incandescent lamps (including halogen) offer a CRI close to 100, while the latest generation of high-quality LED lighting can reach CRI 95+. Today, lighting with CRI 90 and above is preferred in areas requiring high color accuracy (photography, art galleries, textiles, healthcare). A CRI value as high as R9 provides the best color accuracy, offering the closest illumination to the natural look.
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