Painterly Rendering Framework from Compo

sition

Chi ChuZen-Chung Shih

Department of Computer Science National Chiao Tung University, Taiwan

Outline

• Introduction

• The Framework and Results

• Conclusions

Introduction

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 and Results

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

‘ImpBuilding’ Rendering Function

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

Conclusions

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

Questions?