1. Depth-of-Field Rendering by Pyramidal Image Processing07
E U R O G R A P H I C S
Depth-of-Field Rendering by Pyramidal Image Processing
Martin Kraus (TU München) and
Magnus Strengert (Universität Stuttgart)

2. 00 Outline of this Talk 01 Introduction 02 Related work
03 Proposed method
04 Experiments
05 Future work

3. 01 I N T R O D U C T I O N What Is Depth of Field?
The depth in front and beyond the focus plane where objects appear to be in focus
A property of all real optical systems
only virtual pin-hole cameras have infinite depth of field
Used for important photographic and cinematographic techniques

4. photo by Jon Sullivan (http://pdphoto. org/PictureDetail. php

5. photo by "che" (http://commons. wikimedia

6. Classification of Techniques:02
R E L A T E D W O R K
Classification of Techniques:
Splatting [Potmesil & Chakravarty 1982]
Stochastic sampling [Cook et al. 1984]
e.g., in distributed ray tracing or in REYES
state of the art in offline rendering
Pre-filtering [Rokita 1993]
lots of artifacts [Demers 2004]
state of the art in real-time rendering
Blurring of sub-images [Barsky 2004]

7. High Quality in Real Time?02
R E L A T E D W O R K
High Quality in Real Time?
Real-time performance requires:
independence of scene complexity
excludes stochastic sampling
thus: image post-processing of a pin-hole color image and depth map
independence of image synthesis for free
convolution filtering is too expensive
even with FFTs on GPUs
thus: blurring using pyramid algorithms

8. High Quality in Real Time?02
R E L A T E D W O R K
High Quality in Real Time?
High image quality requires:
smooth blurring without interpolation artifacts
pyramid blurring [Kraus & Strengert 2007]
no incorrect color bleeding
excludes pre-filtering
separate blurring of sub-images
disocclusion of semi-transparent pixels
inpainting of colors and depths with pyramid algorithm [Strengert et al. 2006]

9. 03 P R O P O S E D M E T H O D Overview pin-hole image & depth map
decomposition into sub-images 1
disocclusion 2
matting 3
blurring 4
blending of sub-images 5
resulting image

10. 03 P R O P O S E D M E T H O D Decomposition1
decompose into sub-images and cull foreground pixels according to depth map

11. 03 P R O P O S E D M E T H O D Disocclusion2
for each sub-image: disocclude culled foreground (using pyramidal inpainting)

12. 03 P R O P O S E D M E T H O D Matting
for each sub-image: compute alpha-matting according to each pixel's depth

13. 03 P R O P O S E D M E T H O D Blurring4
for each sub-image: blur color and alpha (using pyramidal blurring)

14. 03 P R O P O S E D M E T H O D Blending5
back-to-front blending of all sub-images
result computed in 70.4 ms
(12 sub-images, hardware:
NVIDIA GeForce 7900 GTX)

15. 03 P R O P O S E D M E T H O D Main Features
independent of scene complexity
and independent of image synthesis
interactive perfomance on GPUs
real-time for small circles of confusion
high image quality
avoids artifacts of pre-filtering techniques
let's do some experiments …

16. 04 E X P E R I M E N T S Our Method vs. pbrt
pbrt uses stochastic sampling
Which is which?

17. 04
E X P E R I M E N T S
Our Method vs. pbrt
pbrt
our method

18. 04
E X P E R I M E N T S
Our Method vs. pbrt
Which is which?

19. 04
E X P E R I M E N T S
Our Method vs. pbrt
pbrt
our method

20. 04 E X P E R I M E N T S Can We Break Our Method?
Yes, with a very large lens radius.
pbrt
bleeding gray
too opaque
our method

21. 04 E X P E R I M E N T S Can We Break Our Method?
Video with very large lens radii: eg07.mov
also available at:

22. 05 F U T U R E W O R K Are We there yet?
No, but we avoid typical rendering artifacts of real-time techniques
Specialized variants for better performance and image quality
Alternative blur filters
High-potential application:
gaze-directed focus

23. 06
A C K N O W L E D G M E N T S
The photos appear courtesy of "che" and Jon Sullivan.
The dragon model appears courtesy of the Stanford University Scanning Repository.
The pbrt scene appears courtesy of Gregory Humphreys and Matt Pharr.

24. Thank you! And have a safe trip home! Questions?07
E U R O G R A P H I C S
Thank you! And have a safe trip home! Questions?

25. 07
E U R O G R A P H I C S