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Transfer Color to Grayscale Image

Transfer Color to Grayscale Image. Review:. +. =. Another Example. +. =. Current Literature. Most techniques – Involve heavy human interaction Pseucoloring Movie Industry. Pseudocoloring. c(x, y) = T(f(x, y)) Choice of colormap – determined by human decision.

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Transfer Color to Grayscale Image

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  1. Transfer Color to Grayscale Image

  2. Review: + =

  3. Another Example + =

  4. Current Literature • Most techniques – Involve heavy human interaction • Pseucoloring • Movie Industry

  5. Pseudocoloring c(x, y) = T(f(x, y)) Choice of colormap – determined by human decision

  6. Movie Industry -- Silberg [1998] • Polygonize the image • Color individual components like a color book – human interaction • Track polygons between frames and transfer colors

  7. Reinhard et al. [2001] • Transfer color between two color images • Inspire the algorithm in Welsh’s paper

  8. Main Idea R G Intensity or Luminance B

  9. l Color Space • Goal: minimize correlation between three coordinate axes of the color space • l: luminance channel • : yellow-blue channel • : red-green channel • l color space provides a decorrelated achromatic channel • Transfer chromatic  and  channels from color image to grayscale image without cross-channel artifacts

  10. Algorithm (Details) • Step 1:

  11. RGB l color space

  12. Luminance Remapping • linearly shift and scale the luminance histogram of the source image to fit the histogram of the target image

  13. Algorithm (cont.) • Step 2: Jittered Sampling: 200

  14. Neighborhood Statistics • Weighted average of luminance (50%) and standard deviation (50%) • Neighborhood size: 5x5 pixels

  15. General Algorithm (cont.) • Step 3: ,  channel

  16. l RGB color space Step 4:

  17. Algorithm (cont.) • They also suggest: Swatch + =

  18. Results, Analysis & Discussion + =

  19. Sample Size + = 64x64 30x20 20x10

  20. Neighborhood Size + = 5x5 10x10

  21. Luminance Weight 50% + = 80% 30%

  22. Image Size 64x64 128x128 256x256

  23. Reasons for Problematic Area • Texture correspondence • - Standard Deviation This leads to the extension to SWATCH

  24. Texture correspondence + = + =

  25. Rounding Error

  26. Running Time • 15 seconds to 4 minutes on a Pentium III 900 MHz CPU using optimized MATLAB code • Ours…a few seconds on a Pentium III 1 GHz CPU using optimized VC++ code but…We are using different sized images, so… No comparison!

  27. References • GONZALEZ, R. C. AND WINTZ, P., 1987. Digital Image Processing, Addison-Wesley Publishing, Reading MA • HERTZMANN, A., JACOB, C., OLIVER, N., CURLESS, B., SALESIN., D., 2001. Image Analogies, Proceedings of ACM SIGGRAPH 2002, 341-346 • PITAS, I., Digital Image Processing Algorithms, Prentice Hall, 1993 • REINHARD, E., ASHIKHMIN, M., GOOCH B. AND SHIRLEY, P., 2001, Color Transfer between Images, IEEE Computer Graphics and Applications, September/October 2001, 34-40 • SILBERG, J., 1998. Cinesite Press Article, tttp://www.cinesite.com/core/press/articles/1998/10_00 _98-team.html • WELSH, T., ASHIKHMIN, M. AND MUELLER, K., 2002, Transferring Color to Greyscale Images, SIGGRAPH 2002, 277 - 280

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