Abstract

Over 200 Florida manatee (Trichechus manatus latirostris) carcasses are necropsied each year at the MMPL in St. Petersburg, FL. Carcasses are examined to determine cause of death and to collect life-history information. Objective color assessment is an important component of gross description during necropsy because colors of vital organs change depending on degree of decomposition, disease, and manner of death. Problems with current methods for color assessment include non-standard photographic conditions and individual variations in verbal color descriptions. Color descriptions vary with an individual's color vision or choice of color terms, the lack of a standard reference, and eye fatigue.¹ Inaccuracies of color description are not always recognized. Some histopathologists in UK hospitals were found to be color deficient and unable to accurately diagnose colors on slides.² Doctors with color vision deficiencies (CVD) differ in their abilities to detect and assess abnormalities in clinical photographs.³ We assessed color using the principle that a color can be described by three or more components (e.g., RGB -- red, green, and blue). This method is used in many sciences, the textile industry, marketing, and color television. Color terms, lighting, and numerical specification of colors are all internationally standardized by the Commission Internationale de l'Eclairage (CIE).¹ Other color schemes (e.g., CMYK- cyan, magenta, yellow, black) can be accurately translated into CIE equivalents as long as the color components are defined. To acquire images, we used a Nikon Coolpix 990, with 3.34 mega pixels of resolution, fitted with strobes, and set at a standard distance. Images were analyzed with Adobe Photoshop v. 5.5 to quantify organ colors in two numerical schemes: RGB and CMYK. So far, we have found that RGB is superior to CMYK for our needs. Preliminary results show that color averages from a fresh liver are: R=83, G=32, B=29; decomposed liver under the same lighting has averages of R=I 1, G=I 1, B=I 0. Thus, the R component is high in fresh liver, and in contrast, decomposed liver resembles neutral gray. We hope that improving the methods for of descriptions of organ appearance will improve the overall assessment of each manatee carcass.

References

1.  Clulow, F.W. 1972. Color -- Its Principles and Their Applications. Morgan & Morgan, New York.

2.  Poole, C.J.M., D. J. Hill, J. L. Christie, and J. Birch. 1997. Deficient color vision and interpretation of histopathology slides: cross-sectional study. British Medical Journal 315:1279.

3.  Spalding, J.A. 1999. Colour vision deficiency in the medical profession. British Journal of General Practice 49:469-475.