1. Content-Sensitive Screening in Black and White
Hua Li and David Mould
Presented by Hua Li
2018/11/9

2. Outline Introduction Previous Work Our Method
Discussion and Future Work
Presented by Hua Li
2018/11/9

3. Introduction Screening
A process for printing by passing ink through a perforated screen (or pattern) over a region.
Screen2
Screen1
Pattern2
Pattern1
Presented by Hua Li
2018/11/9

4. Previous Methods Original Image Our Type I (Main Direction)
Dithering Method (Ulichney, 1987)
Manga Screening (grayscale) (Qu et al., 2008)
Our Type I (Edge-exclusion)
Presented by Hua Li
2018/11/9

5. Motivated by Contrast-Aware Halftoning
An variant of error diffusion algorithm
The contrast-aware weight distribution
The priority-based scheme
Original Image
Our Contrast-Aware Halftoning [Li and Mould 2010]
Presented by Hua Li
2018/11/9

6. Overview of Our Method Pattern Assignment OR Pattern Generation
Presented by Hua Li
2018/11/9

7. PartI: Pattern Assignment
Green: medium degree of content
White: background trivial area
Mean-shift segmentation
[Comaniciu
and Meer, 2002]
Gradient map
Yellow: uniform regions
Blue: highly textured
Presented by Hua Li
2018/11/9

8. Our Method—Pattern Generation (I)
Type I: Exclusion-based Masks
Presented by Hua Li
2018/11/9

9. Our Method—Pattern Generation (I)
Type I: Tone changes
Presented by Hua Li
2018/11/9

10. Our Method—Pattern Generation (I)
Random assignment without content consideration
Edge-exclusion
Type I: Main direction
Presented by Hua Li
2018/11/9

11. Dithering
Manga Screening
Our Type I
2018/11/9

12. Our Method—Pattern Generation (II)
(a)Pixels on pattern edges from input images
(b)Pixels on ETF feature edges
( c) The rest pixels
A multi-stage process
Stage I:
Stage II:
Stage III:
Presented by Hua Li
2018/11/9

13. Our Type II Dithering Method Manga Screening Our Type I
Presented by Hua Li
2018/11/9

14. More Comparisons: Manga Screening Our Type II Our Type II Our Type I
Dithering
Presented by Hua Li
2018/11/9

15. Discussion Both structure-preserving screening with natural looking.
An automatic method.
Powerful extensions from the multi-stage process.
Performance: faster than manga screening.
Open to color extensions.
Presented by Hua Li
2018/11/9

16. Presented by Hua Li hli1@connect.carleton.ca
2018/11/9

17. Presented by Hua Li hli1@connect.carleton.ca
2018/11/9

18. Future Work
Refine the content-sensitive assignment and improve the multi-stage process;
Introduce high-quality patterns into our method;
Extend to color screening.
Presented by Hua Li
2018/11/9

19. Acknowledgement Thanks to:
permission to use their original images and their results from Yingge Qu;
grants from NSERC and Carleton University.
Presented by Hua Li
2018/11/9