Light Souce Descriptions

• D75 (7500K)
• D65 (6500K)
• D50 (5000K)
• Ultra Violet
• Cool White Fluorescent (CWF)
• Illuminant A
• Warm White Fluorescent (WWF)
• TL84 (Europe)
• TL830
• TL835
• Ultralume 30 (U30 or 30U)
• Ultralume 35 (U35 or 35U)

D75 (7500K) - A bluish colored light source originally used for grading cotton and other evaluation applications. It has been replaced by D65 as the standard source for these applications. It accentuates blue and subdues green and red. It is derived from the light coming in a north facing window in the northern hemisphere at noon at various times throughout the year. It is commonly called “North Sky Daylight.”

D65 (6500K) - A light bluish colored light source used in color matching applications of paints, plastics,textiles, raw inks, and other manufactured products. It is the only daylight source that was actually measured. The other daylight sources (D75 and D50) were mathematically derived from these measurements. It accentuates blue and subdues green and red. Commonly used as a primary light source in color measurement instrumentation. It is derived from the average of measurements made of light coming in a north facing window in the northern hemisphere on an overcast day at various times through the day at various times throughout the year.

D50 (5000K) - A near white light source used in the evaluation of graphic arts and imaging applications. It has similar amounts of red, green, and blue energy. It neither accentuates nor subdues color, a prime requirement when viewing press sheets and original images (i.e., photographs) since they usually have many colors within the product to be evaluated.

Ultra Violet (UV) - Light energy not normally visible to the human eye, but which is present in natural daylight. UV energy has the ability to excite certain substances (dyes/pigments/chemicals) within a sample causing them to emit light in the visible spectrum, usually in the blue region. These substances are used in various products to “brighten” colors, particularly whites. It is necessary to include correct amounts of UV energy in a color matching system to allow for optimum simulations of natural daylight.

Cool White Fluorescent (CWF) - A wide band single phosphor fluorescent source commonly used in commercial lighting applications in North America. It is characterized by emitting high amounts of green energy, with a color temperature of approximately 4100K. It has a CRI or approximately 62.

Illuminant A (2865K) is a common household light bulb that is yellowish red in color.

Warm White Fluorescent (WWF) - A wide band single phosphor fluorescent source used in commercial lighting applications in North America. It is characterized by emitting high amounts of yellow/red energy, with a color temperature of approximately 3000K. It has a CRI of approximately 53.

TL84 (Europe) - A narrow band tri-phosphor fluorescent source originally designed for commercial lighting applications outside North America. It is characterized by emitting high amounts of green energy, with a color temperature of approximately 4100K. It has a CRI of approximately 86.

TL830 - A narrow band tri-phosphor fluorescent source originally designed for commercial lighting applications outside North America. It is characterized by emitting high amounts of yellowish red energy, with a color temperature of approximately 3000K. It has a CRI of approximately 86.

TL835 - A narrow band tri-phosphor fluorescent source originally designed for commercial lighting applications outside North America. It is characterized by emitting high amounts of reddish yellow energy, with a color temperature of approximately 3500K. It has a CRI of approximately 86.

Ultralume 30 (U30 or 30U) - A narrow band tri-phosphor fluorescent source originally designed for commercial lighting applications in North America where energy savings is required. It is characterized by emitting high amounts of yellowish red energy with a color temperature of approximately 3000K. It has a CRI of approximately 85.

Ultralume 35 (U35 or 35U) - A narrow band tri-phosphor fluorescent source originally designed for commercial lighting applications in North America where energy savings is required. It is characterized by emitting high amounts of reddish yellow energy with a color temperature of approximately 3500K. It has a CRI of approximately 85.

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