Color Science Laboratory

This Laboratory mainly provide consultant services including color imaging algorithm development, spectral color matching, color matching of dyeing and paint, fluorescent color matching, color measurement of gemstones, and instrumental color grading of pearls and colored stones. We have developed several types of daylight sources and display light sources using incandescent lamps and colored glass filters. Currently we provide colored glass filters and attachments for MR16 and MR11 incandescent lamps.

We are doing research projects in the field of color vision, including the systematic color vision theory, negative feedback control of the visual system, chromatic adaptation, and lightness adaptation.

Spectral Matching of Color

A spectral reflectance modified Neugebauer theory was developed by Liu(1991). This theory uses the equivalent spectral reflectance(ESR) to represent the optical effects of a ink layer. It can predict the thinknesses or the dot area ratios of the primary printing colors. A target color is best matched wavelength by wavelength. This theory was tested using the 3M Matchprint proof. The spectral reflectances of the proof colors match that of sample color very well.

This theory can be directly used to any color materials for different types of printers, since the spectra of target colors are matched by that of the primary colors.

Liu, Y(1991) Spectral reflectance modification of Neugebauer equations, TAGA Proceedings, pp. 154-172.

Attachments for MR16 and MR11 Incandescent Lamps

The attachment includes three parts: a colored glass filter, a self-attaching hood, and a O-ring. There are four types of colored glass filters: 1. UV and IR cut filters, 2. color temperature increasing filters, 3. color filters and other special effect filters, and 4. thin film filters.

The attachment with a UV and IR cut filter is designed to cut UV and IR from an incandescent lamp, and to slightly increase color temperature to about 3500K. This type of attachment is widely used for art display in museums, gemstones in jewelry stores. The UV and IR radiations from an incandescent light is harmful to arts. They can make a paint fade due to UV radiation, and heat due to IR radiation. This attachment can significantly reduce UV radiation shorter than 360 nm and absorb most IR radiation. Another advantage is the 3500K color temperature which makes color appear more perceptible in museums and stores.

The attachment with a color temperature increasing filter is designed to simulate daylight at different phases. The most used daylight simulator is D65 operating at 6500K. D50 is the standard daylight simulator for the graphic arts industries. The daylight simulators with the attachments are superior than fluorescent daylight simulators for color rendering, because they do not have the line spectra in all fluorescent daylight simulators.

We can design and produce colored glass filters, thin film filters, polarize filters, and crystal filters for the attachment to meet the specified requirements from customers. We can provide primary color filters, band pass filter, multiband filters, infrared filters, and  color  temperature reducing filter.

Alexandrite Effect Sample Set

Alexandrite effect refers to color change under different light sources. This effect is a non-color-constancy phenomenon. It is classified into four types based on the pair of illuminants used to produce the color changes. Our Alexandrite Effect Sample Set contains two samples to represent  the two most important types: type 1 and type 2. The category 1 sample is a synthetic alexandrite which shows a greenish blue color under an daylight or a fluorescent light, and reddish purple under an incandescent light. The category 2 sample may be a synthetic sapphire, garnet, or colored glasses. It shows similar color under daylight and incandescent light, but differs under a fluorescent light.

This Alexandrite Effect Sample Set is for color science research, vision science research, psychophysics research, color education, gem trade, and collection.