Painterly Rendering Framework from Compo
sition
Chi ChuZen-Chung Shih
Department of Computer Science National Chiao Tung University, Taiwan
Painterly Rendering
• Typical painterly rendering problem– Ordinary image
another image with particular painting style.
– Input can also come from other format.
Pointillism
Various Approaches
for developersimple to implement
for userfull control
requires art background
time consuming
High InteractionPainter
Photoshop...
Low Interaction
Chi06, Ols05, Hay04, Her98,
Hae90......
for developerhard to translate
artistic rules
for usereasy to use
less control
control by parameters
Where We Focus
The Framework
• The framework is inspired by Willats (1997) “Art and Representation”.– “...describe the representational systems in pictures
and the functions of these systems, independently of any historical or developmental consideration...”
– Drawing System• projection
– Denotation System• rendering
The Framework (cont.)
Primitive System
Rendering System
Mark System
InputList of
Primitives
List of Stroke
Definitions
Canvas
Denotation System
Implicit Drawing System
Image Processing Front End• To construct a framework, we unify inputs.
• Input contains a hierarchy of objects
each of which contains:– Object Information
– Object Relation Information
– Primitive Information
• There are a lot of algorithms dealing with converting raw inputs to our input.
Primitive System• Primitive System
– A set of operators changing the properties of primitives.
• Primitive Properties– Shape: two-dimensional masking image.– Color: two-dimensional color buffer.– Extendedness: human perception of shape.
• Four kinds of operators– Merging, Subtracting, Selection, and Sorting– Conversion– Shape Modifier– Color Modifier
Rendering System• Rendering Function
– Primitive List of Stroke Definitions
– It can access information – input object hierarchy and Canvas
• Stroke Definitions– initial point
– path (list of control points)
– cross-section at control points
– color at control points
Example: ‘ImpBuilding’ Rendering Function• Synthesize series of paintings by Monet during 1899~1901.
– buildings, rivers and skies immersed in the morning mist
‘ImpBuilding’ Rendering Function
• The algorithm– color
• automatically find the two most distinct base colors: surrounding color and instinct color
• these two colors are blended to form stroke color
– path• modified to follow the shape of the object
– initial point• seeded randomly to mimic casual painting effects
Module Composition• Basic Idea
– instead of complete styles, partial styles are developed
• artist’s creation can not be realized by algorithm
• users can apply their creation
• Divide rendering function into four modules. – each one is responsible for one kind of stroke definitions
• New style is created by simply choosing these modules from existing rendering functions and combining them.
Parameter Hierarchy• Most approaches adopt parameters to control the v
ariation of styles. – derived from algorithm designing stage– unintuitive for end-users
• The framework provides a hierarchical representation of parameters.– style parameters– user parameters– system-dependent parameters– system-independent parameters
Conclusion
• A flexible painterly rendering framework is presented.– division of the framework is based on the actual
process of painters– user interaction through module composition– easy usage by parameter hierarchy