Portrait artists using oils, acrylics or pastels use a specific but open human vision methodology to create a painterly portraitof a live sitter. When they must use a photograph as source, artists augment their process, since photographs have: differentfocusing - everything is in focus or focused in vertical planes; value clumping - the camera darkens the shadows and lightensthe bright areas; as well as color and perspective distortion. In general, artistic methodology attempts the following: from thephotograph, the painting must u27simplify, compose and leave out what?s irrelevant, emphasizing what?s importantu27. Whileseemingly a qualitative goal, artists use known techniques such as relying on source tone over color to indirect into asemantic color temperature model, use brush and tonal "sharpness" to create a center of interest, lost and found edges tomove the viewers gaze through the image towards the center of interest as well as other techniques to filter and emphasize.Our work attempts to create a knowledge domain of the portrait painter process and incorporate this knowledge into a multispaceparameterized system that can create an array of NPR painterly rendering output by analyzing the photographic-basedinput which informs the semantic knowledge rules.
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