ELEC 243 Lab

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Requirements

1. Your system must indicate the relative diffuse reflectance of the sample at each of three different wavelengths, chosen to be representative of red, green, and blue.
2. The reflectance at each wavelength should be displayed in percent.
3. Your system should also provide a quantitative measure of the similarity in color between two samples. Your measure need not have any specific physical or perceptual meaning, but should yield small values for samples which are close togetner in a standard color system (e.g. Munsell), large values for colors which are far apart, and zero for successive measurements of the same object.
4. Your system should handle samples as small as 5/8 inch square.
5. You should design the system so the measurement can be made by someone not familiar with the system, using written instructions you supply. A measurement should not take longer than 1 minute.

Background and Resources

1. Reflectance is a measure of the fraction of incident optical power that is reflected from a surface, usually expressed in percent. Check out Wikipedia for a quick reference.
2. You will have available LEDs of various colors, including "white." Also available are colored filters that can be placed in front of a light source or detector. You may use as many sources, filters, and detectors as you wish.
3. Optical components, such as lenses, prisms, simple gratings, etc., are also available and may be used freely.
4. Black and White reference sheets for calibration will be available.

Evaluation

1. Your system will be tested with standard color samples, such as Munsell, Macbeth, or Pantone.
2. It must accurately indicate the reflactance values of the samples, and must correctly indicate the degree of match of pairs of samples.
3. The human interface and ease of use will be evaluated.