1. Painterly Rendering Framework from Composition Chi Chu Zen-Chung Shih Department of Computer Science National Chiao Tung University, Taiwan

2. Outline Introduction The Framework and Results Conclusions

3. Introduction

4. Painterly Rendering Typical painterly rendering problem –Ordinary image  another image with particular painting style. –Input can also come from other format. Pointillism

5. Various Approaches for developer simple to implement for user full control requires art background time consuming High Interaction Painter Photoshop... Low Interaction Chi06, Ols05, Hay04, Her98, Hae90...... for developer hard to translate artistic rules for user easy to use less control control by parameters Where We Focus

6. The Framework and Results

7. 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

8. The Framework (cont.) Denotation System Implicit Drawing System

9. 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.

10. 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

11. 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

12. Example: ‘ImpBuilding’ Rendering Function Synthesize series of paintings by Monet during 1899~1901. –buildings, rivers and skies immersed in the morning mist

13. ‘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

14. ‘ImpBuilding’ Rendering Function

15. 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.

16. Parameter Hierarchy Most approaches adopt parameters to control the variation 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

26. Conclusions

27. 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

28. Questions?