Here's a list of my patents as of December 2, 2020. Each of the patents is linked to its page on Google.
All of the patents listed here are subject to the following patent grant:
Whereas, Raph Levien (hereinafter "Inventor") has obtained patent protection for related technology (hereinafter "Patented Technology"), Inventor wishes to aid the the GNU free software project in achieving its goals, and Inventor also wishes to increase public awareness of Patented Technology, Inventor hereby grants a fully paid up, nonexclusive, royalty free license to practice the patents listed below ("the Patents") if and only if practiced in conjunction with software distributed under the terms of any version of the GNU General Public License as published by the Free Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111. Inventor reserves all other rights, including without limitation, licensing for software not distributed under the GNU General Public License.
| 9230350 | Method and apparatus for interactive curve generation |
| 8810579 | Method and apparatus for interactive curve generation |
| 8520003 | Method and apparatus for interactive curve generation |
| 6097855 | Method and apparatus for image rotation |
| 5991513 | Method and apparatus for suppressing moire patterns |
| 5917614 | Method and apparatus for error diffusion screening of images with improved smoothness in highlight and shadow regions |
| 5544258 | Automatic tone correction of images using non-linear histogram processing |
| 5524162 | Method and apparatus for adaptive sharpening of images |
| 5442461 | Screen generation for halftone screening of images with reduction of irrational correction artifacts |
| 5404137 | High speed transition signalling communication system |
| 5402726 | Register mark |
| 5388517 | Method and apparatus for automatic alignment of objects and register mark for use therewith |
| 5365602 | Integrated half-tone screening and enlarging using an enlargement mapping pattern having linked, unique pattern segments |
| 5337264 | Time reversal gaussian approximation filter |
| 5331429 | Digital generation of halftone images with error diffusion and frequency matched periodic screen rulings |
| 5315406 | Screen generation for halftone screening of images using arbitrary distribution of transformed screen coordinates |
| 5307181 | Screen generation for halftone screening of images using scan line segments of oversized screen scan lines |
| 5291310 | Screen generation for halftone screening of images |
| 5276535 | Method and apparatus for halftoning of images using grayscale error diffusion |
| 5218386 | Eyeglasses with spectral color shift |
| 5155588 | Color correction and apparatus for photographic reproduction |
| 5055942 | Photographic image reproduction device using digital halftoning to screen images allowing adjustable coarseness |
| 4523271 | Software protection method and apparatus |