Original scientific paper

Video Subtraction: Dynamic Temporal Change Versus Intrinsic Colour Instability

Allan G. Farman ; School of Dentistry The Universitiy of Louisville Kentacky 40292, USA
Taeko T. Farman ; School of Dentistry The Universitiy of Louisville Kentacky 40292, USA
William Engilman ; School of Dentistry The Universitiy of Louisville Kentacky 40292, USA
Darren B. Earl ; School of Dentistry The Universitiy of Louisville Kentacky 40292, USA

Abstract

Objectives: To evaluate digital subtraction of still video images to show temporal change in a simulated oral hygiene effectiveness trial.
Methods: An acrylic stent was used for the accurate repositioning
of a Stoma Vision (STV) video camera (Trophy Radiologie, Vincennes,
France) to view the anterior teeth and gingivae of a DXTRR manikin
(Dentsply/Rinn, Elgin, Illinois). Images were stored in binary form (16
bit: 5 red; 5 blue: 6 green) within the RVG/STV-PC software provided
by the manufacturer of the camera. Red wax was applied to the manikin to simulate changes in the coverage o f plaque disclosing solutions and gingival inflammation. Videos were also taken over time without manipulation o f the model to evaluate intrinsic colour instability o f the system. Image subtraction followed the formula: g(x1,y)=f(x1,y)-h(x1,y), computing the differences of corresponding pixel from f and h, given the new image y. Histogram analysis for each (red, blue and green) followed the discrete function P(rk)=N/n, where rk is the kth colour level, Nk is the number of pixels in the image with that color level and k=0,l,2,...L~1 is range.
Results: Subtraction o f video images provided solid evidence o f dynamic temporal change where colour contrast was substantial (e.g.
placing a wax red dot over the crown of a tooth). Intrinsic colour instability due to the temperature of light source among other factors was seen over time, especially when the STV was activated for more than one hour. Conclusions: Video subtraction shows potential as a method to quantify changes in disclosed dental hygiene status or tooth coloration over time; however, changes due to colour temperature modification over time need to be factored.

Keywords

dental hygiene; digital imaging; digital subtraction; image processing

Hrčak ID:

97862

URI

https://hrcak.srce.hr/97862

Publication date:

15.6.1998.

Article data in other languages: croatian

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