Pencil Drawing Production Cewu Lu, Li Xu, Jiaya Jia

Speaker: Ying-Jou Chen

AmazingDSP

Proposed Approach

• Line Drawing• Tone Mapping

Line Drawing

• Idea… contour might be related…

Sobel Filter

Edge?

Not enough…

Line DrawingNot Simply Edges…

Line Drawing- Curve

• Idea… direction detection

Line Drawing- Line Crossing

• Idea… CONVOLUTION• Effect of extension

Line Drawing

⨂ ⨂ ⨂

+¿ +¿

Line Drawing

⨂ ⨂ ⨂

+¿ +¿

Magically….

DONE!

Tone Mapping

Histogram

Histogram

# of pixels

pixel value

Pencil ToneNatural Tone

Histogram Equalization

Tone Mapping

• Model the shape by….

Laplacian Distribution

Uniform Distribution

Gaussian Distribution

Pencil ToneNatural Tone

DONE!DONE!

Texture Rendering

Pencil Texture Rock Texture Chinese Drawing Texture

Texture Rendering

𝜷=𝟎 .𝟐𝜷=𝟎 .𝟔

𝜷=𝟏 .𝟎𝜷=𝟏 .𝟒

Texture Rendering

To each pixel, we hope that…

𝑷 (𝒙) 𝑱 (𝒙)

Pencil Tone

𝑷 (𝒙)𝜷( 𝒙)≈ 𝑱 (𝒙)

Texture Rendering

Smooth

𝜷∗

Other examples

Reference

• "Combining Sketch and Tone for Pencil Drawing Production", Cewu Lu, Li Xu, Jiaya Jia , International Symposium on Non-Photorealistic Animation and Rendering (NPAR 2012), June, 2012

• ADMM optimization • YUV RGB transformation http://zh.wikipedia.org/wiki/YUV • Author’s website http://appsrv.cse.cuhk.edu.hk/~xuli