Exposure of Underdrawings in Oil Paintings Through IR Analysis Chad B. Weiner Dr. Jon Arney May 8, 1998.

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  • Slide 1
  • Exposure of Underdrawings in Oil Paintings Through IR Analysis Chad B. Weiner Dr. Jon Arney May 8, 1998
  • Slide 2
  • Review - Underdrawings zPreparatory drawings applied directly to a ground and then covered by the oil painting. zMedia used ymostly charcoal ypencil ychalk
  • Slide 3
  • Review - IR Reflectography zInfrared radiation passes through the paint layer while being reflected by the charcoal substrate.
  • Slide 4
  • Aims of Research zTo improve current IR underdrawing analysis techniques (Reflectography) using image processing methods. zTo develop a means of removing the paint layer from the underdrawing using an equation derived from Kubelka-Munk theory.
  • Slide 5
  • Research Methodology zSamples - charcoal drawings sketched on a canvas & painted over by flake-white oil-based paint. zVIS images captured using a COHU camera. zIR images captured using a COHU camera covered by an Infrared filter.
  • Slide 6
  • Data Analysis zPreliminary analysis - IMLAB software. yUD(i, j) = VIS(i, j) - IR(i, j)
  • Slide 7
  • Data Analysis IR Image Subtraction
  • Slide 8
  • Programming zVisual Basic Program yK, n -> variables
  • Slide 9
  • Results Image Subtraction K=3.0, n = 1.3
  • Slide 10
  • Results IR K=3.0, n = 1.3
  • Slide 11
  • Future Research Possibilities zIncorporate Kubelka-Munk Theory yConvert Grayscale Values from camera output into Reflectances yDetermine the Absorption Coefficient ySolve for the Ground Reflectance (Underdrawing)
  • Slide 12
  • Conclusions zUnable to derive an equation from Kubelka-Munk Theory zCompleted research provides enough evidence that it is possible to remove the paint layer and other artifacts from an underdrawing
  • Slide 13
  • The End

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