Digital halftoning quantizes a grayscale image tone bit per pixel for display and printing on binary devices. It is a crucial technique used in digital printers to convert a continuous tone image into a pattern of black and white dots. Halftoning is used since printers have a limited availability of inks and cannot reproduce all the color intensities in a continuous image. Error Diffusion is an algorithm in halftoning that iteratively quantizes pixels in a neighborhood dependent fashion. Halftones are created through a process called dithering. The standard error diffusion algorithm was introduced by Floyd and Steinberg. Though it has the advantage of producing high visual quality images at low cost ,still it suffers from the problem of introducing worm-like artifacts in smooth regions. To overcome such problem, a chaotic and edge enhanced error diffusion method for image enhancement is proposed.

1. Schumann. T, Susanti,A. R. D. "FPGA design for image processing using a GUI of a web-based VHDL Code Generator," Proc. of IEEE International Conference on Visual Communications & Image Processing (VCIP), 2011.
2. Swagata Samanta , Soumi Paik, Amlan Chakrabarti, "Design & Implementation of Digital Image Processing using FPGA" LAP Lambert Academic Publishing, 2011.
3. C. -Y. Su and Y. -L. Shiue, "Edge-Adaptive Error Diffusion Using Chaotic Threshold Modulation," Proc. of IEEE International Midwest Symposium on Circuits and Systems, MWSCAS 2009, pp. 718-721, August 2-5, 2009.
4. W. -C. Kao, J. -A. Ye, and C. Lin, "Image quality improvement for electrophoretic displays by combining contrast enhancement and halftoning techniques," Proc. of IEEE International Conference on Consumer Electronics, 11. 2-2, 2009.
5. C. -Y. Hsu, C. -S. Lu, and S. -C. Pei, "Compression of halftone video for electronic paper," Proc. of IEEE International Conference on Image Processing, pp. 1600-1603, 2008.
6. J. -M. Guo, "Improved block truncation coding using modified error diffusion," Electronics Letters, vol. 44, no. 7, pp. 462-464, March 2008.
7. Z. -J. Liu, Z. -H. Liang, and C. -L. Liu, "3-dimensional error diffusion method based on edge detection for digital display devices," IEEE Trans. Consumer Electronics, vol. 53, no. 2, pp. 239-242, May 2007.
8. T. Lin, "Probabilistic error diffusion for image enhancement," IEEE Trans. on Consumer Electronics, vol. 53, no. 2, pp. 528-534, May 2007
9. X. Li, "Edge-directed error diffusion halftoning," IEEE Signal Processing Letters, vol. 13, no. 11, pp. 688-690, Nov. 2006.
10. D. Kacker and J. P. Allebach, "Joint halftoning and watermarking," IEEE Trans. Image Processing, vol. 51, no. 4, pp. 1054-1069, 2003.
11. N. Damera-Venkata and B. L. Evans, "Adaptive threshold modulation for error diffusion halftoning," IEEE Trans. Image Processing, vol. 10, no. 2, pp. 104-116, Feb. 2001.
12. V. Ostromoukhov, R. D. Hersch, and I. Amidror, "Rotated dispersion dither: a new technique for digital halftoning," Proc. of SIGGRAPH'94, pp. 123-130, 1994.
13. K. Knox and R. Eschbach, "Threshold modulation in error diffusion," J. Electron. Imaging, vol. 2, pp. 185-192, 1993.
14. H. -O. Peitgen, H. Jurgens, D. Saupe, Chaos and Fractals, Springer- Verlag New York, 1992.
15. R. Eschbach and K. T. Knox, "Error-diffusion algorithm with edge enhancement," Journal of Optical Society of America, vol. 8, no. 12, pp. 1844-1850, Dec. 1991 .
16. R. Ulichney, "Dithering with blue noise," Proc. IEEE, vol. 76, pp. 56-79, Jan. 1988.
17. R. W. Floyd and I. Steinberg, "An adaptive algorithm for spatial grayscale," Proc. SID, vol. 17, no. 2, pp. 75–78, 1976.
18. R. Ulichney, Digital Halftoning. Cambridge, MA: MIT Press, 1987.
19. P. Stucki, "Mecca—A multiple-error correcting computation algorithm for bi-level image hardcopy reproduction," Tech. Rep. RZ1060, IBM Res. Lab. , Zurich, Switzerland, 1981.
20. J. F. Jarvis, C. N. Judice, and W. H. Ninke, "A survey of techniques for the display of continuous-tone pictures on bilevel displays," Comput. Graph. Image Process, vol. 5, pp. 13–40, 1976.

Digital Halftoning Electronic Paper Field Programmable Gate Array Edge Enhancement.