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A Non-Photorealistic Rendering of Seurat’s Pointillism

A Non-Photorealistic Rendering of Seurat’s Pointillism. Computer Graphics Workshop 2006. Hui-lin Yang Chuan-kai Yang National Taiwan University of Science and Technique. Outline. Motivation Pointillism of Seurat NPR of Seurat’s Pointillism Result Conclusions & Future Work. Motivation.

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A Non-Photorealistic Rendering of Seurat’s Pointillism

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  1. A Non-Photorealistic Rendering of Seurat’s Pointillism Computer Graphics Workshop 2006 Hui-lin Yang Chuan-kai Yang National Taiwan University of Science and Technique Computer Graphics & Multimedia Lab. NTUST

  2. Outline • Motivation • Pointillism of Seurat • NPR of Seurat’s Pointillism • Result • Conclusions & Future Work Computer Graphics & Multimedia Lab. NTUST

  3. Motivation • Pointillism painting • tedious process • long time to finish • Current techniques • generic techniques • too general to faithfully reflect all the features of pointillism Computer Graphics & Multimedia Lab. NTUST

  4. Pointillism of Seurat • Features • Eleven colors • Halo & crease effect • Complementary colors • Divisionism Computer Graphics & Multimedia Lab. NTUST

  5. Eleven Colors • Sunlight → triangular prism • red,orange,yellow,green,blue,purple intermediate colors “eleven colors” Computer Graphics & Multimedia Lab. NTUST

  6. Halo & Crease Effects • “Sunday afternoon on the island of La Grande Jatte” • “Young woman powdering herself” Computer Graphics & Multimedia Lab. NTUST

  7. Complementary Colors • Purpose • make the original colors more prominent • Definition • Chevreul’s Color Circle Computer Graphics & Multimedia Lab. NTUST

  8. Divisionism • Optical mixture • Additive mixture • Natural & dazzling color Computer Graphics & Multimedia Lab. NTUST

  9. Outline • Motivation • Pointillism of Seurat • NPR of Seurat’s Pointillism • Result • Conclusions & Future Work Computer Graphics & Multimedia Lab. NTUST

  10. NPR of Seurat’s Pointillism • Goal input image output image Computer Graphics & Multimedia Lab. NTUST

  11. Process crease enhancement crease edge edge detection silhouette edge input image silhouette enhancement color space transformation color disturbance intermediate layer complementary colors background layer segmentation output image Computer Graphics & Multimedia Lab. NTUST

  12. Dot Property • Color • Size • Position • Shape • Direction Computer Graphics & Multimedia Lab. NTUST

  13. Dot Color • Chevreul’s Color Circle with 72 hues HSVcolor space Computer Graphics & Multimedia Lab. NTUST

  14. Hmax H= 0 (360) H= 120 C H= 240 Hmin 1 3 0：4 1：3 2：2 3：1 4：0 4 2 outputdot 2x2pattern mix ratio Color Division inputcolor min, max hue value C (300, 1, 0.5) color table Computer Graphics & Multimedia Lab. NTUST

  15. Dot Size • “Entrance to the Port of Honfleur” • reproduction: 20x20 cm original painting: 54x65cm→ dot size: 9~17pixels • background layer: 5 pixelsintermediate layer: 9~17pixels Computer Graphics & Multimedia Lab. NTUST

  16. Dot Position • Poisson disks Complementary color:distance = 20 pixels Background layer: distance= 3 pixels Intermediate layer: distance= 5~9 pixels Computer Graphics & Multimedia Lab. NTUST

  17. Dot Shape • Selection pool • random selection • principle axis → rotation Computer Graphics & Multimedia Lab. NTUST

  18. A Dot Orientation P gradient Computer Graphics & Multimedia Lab. NTUST

  19. Background Layer crease enhancement crease edge edge detection silhouette edge input image silhouette enhancement color space transformation color disturbance intermediate layer complementary colors background layer segmentation output image Computer Graphics & Multimedia Lab. NTUST

  20. Background Layer • Segmentation input image (640x427) # regions: 498 Computer Graphics & Multimedia Lab. NTUST

  21. Background Layer • Rendering L*max Computer Graphics & Multimedia Lab. NTUST

  22. Intermediate Layer crease enhancement crease edge edge detection silhouette edge input image silhouette enhancement color space transformation color disturbance intermediate layer complementary colors background layer segmentation output image Computer Graphics & Multimedia Lab. NTUST

  23. Intermediate Layer • Color perturbation L* -Hm +Lm p -Sm +Sm -Lm +Hm Computer Graphics & Multimedia Lab. NTUST

  24. Edge Enhancement crease enhancement crease edge edge detection silhouette edge input image silhouette enhancement color space transformation color disturbance intermediate layer complementary colors background layer segmentation output image Computer Graphics & Multimedia Lab. NTUST

  25. Edge Detection • Smoothing • Gradient magnitude & orientation • Nonmaxima suppression • Thresholding Canny edge detection Computer Graphics & Multimedia Lab. NTUST

  26. Thresholding silhouette crease Nonmaxima suppression Computer Graphics & Multimedia Lab. NTUST

  27. Silhouette Enhancement • Halo effect • enhancement range = 40 Computer Graphics & Multimedia Lab. NTUST

  28. Crease Enhancement • Add detail • enhancement range: r = 3 Computer Graphics & Multimedia Lab. NTUST

  29. Complementary Color background layer intermediate layer silhouette enhancement crease enhancement Computer Graphics & Multimedia Lab. NTUST

  30. Hnear Complementary Color Cp ??? Hp Computer Graphics & Multimedia Lab. NTUST

  31. Edge Enhancement background layer intermediate layer silhouette enhancement crease enhancement complementary color Computer Graphics & Multimedia Lab. NTUST

  32. Result vs. Seurat Seurat result color division halo effect Computer Graphics & Multimedia Lab. NTUST

  33. Result vs. Hertzmann source image photoshop Hertzmann our result Computer Graphics & Multimedia Lab. NTUST

  34. Resultvs. Hays source image photoshop Hays our result Computer Graphics & Multimedia Lab. NTUST

  35. Resultvs. Luong source image photoshop Hays our result Computer Graphics & Multimedia Lab. NTUST

  36. Resultvs. Jings source image photoshop Hays our result Computer Graphics & Multimedia Lab. NTUST

  37. Conclusion & Future Work • Faithfully perform a NPR system for Seurat’s pointillism • feature simulation • Future work • reduce parameter → automation • simulate other impressionism style • extend to 3D space Computer Graphics & Multimedia Lab. NTUST

  38. ~ THE END~ Thank you !!! Computer Graphics & Multimedia Lab. NTUST

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