Transcript Pencil Drawing Production", Cewu Lu, Li Xu, Jiaya Jia

Pencil Drawing Production
Cewu Lu, Li Xu, Jiaya Jia
Speaker: Ying-Jou Chen
Amazi
ng
DSP
Proposed Approach
• Line Drawing
• Tone Mapping
Line Drawing
• Idea… contour might be related…
Edge?
Sobel Filter
Line Drawing
Not 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
Natural Tone
Pencil Tone
Histogram Equalization
Tone Mapping
• Model the shape by….
Gaussian Distribution
Uniform Distribution
Laplacian Distribution
Natural Tone
Pencil Tone
DONE!
Texture Rendering
Pencil Texture
Rock Texture
Chinese Drawing
Texture
Texture Rendering
𝜷 = 𝟎. 𝟐
𝜷 = 𝟎. 𝟔
𝜷 = 𝟏. 𝟎
𝜷 = 𝟏. 𝟒
𝑷(𝒙)  𝑷(𝒙)𝜷
Texture Rendering
𝜷(𝒙) ≈ 𝑱(𝒙)
𝑷(𝒙)
To each pixel, we hope that…
Pencil Tone
𝑷(𝒙)
𝑱(𝒙)
Texture Rendering
𝑃(𝑥)𝛽(𝑥) ≈ 𝐽(𝑥)
∗
𝜷
∗
𝛽 = 𝑎𝑟𝑔 min 𝛽 ln 𝑃 − ln 𝐽
𝛽
𝑇=𝑃
𝛽∗
2
2
+ λ 𝛻𝛽
Smooth
2
2
Other examples
Reference
• "Combining Sketch and Tone for Pencil Drawing Production",
Cewu Lu, Li Xu, Jiaya Jia , International Symposium on NonPhotorealistic 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