Dr. Ing. Rudolf Hell GmbH
139Patents
0Active
139Granted
42Portfolio score
Filing activity: Apr 25, 1974 → Aug 17, 1990
Most-cited patents
| Patent | Title | Area | Cited by | Status |
|---|---|---|---|---|
| US4414635A | Method and circuit for recognition of colors | Physics | 103 | Expired |
| US4577219A | Method and an apparatus for copying retouch in electronic color picture reproduction | Electricity | 70 | Expired |
| US4700235A | Method and apparatus for producing half-tone printing forms with rotated screens on the basis of randomly selected screen threshold values | Electricity | 68 | Expired |
| US4499489A | Production of screen printing blocks | Electricity | 67 | Expired |
| US4821114A | Opto-electronic scanning arrangement | Mechanical Engineering; Lighting; Heating | 56 | Expired |
| US4623973A | Method and apparatus for the recognition of hues and colors | Physics | 50 | Expired |
| US4583116A | Method and apparatus for eliminating defects in images in polychromatic printing due to faulty registration of superimposed printing of color separations | Electricity | 46 | Expired |
| US4121259A | Method for digital run-length coding with redundance reduction for transmission of binarily coded picture informations | Electricity | 44 | Expired |
| US4639770A | Method and circuit arrangement for simulating a multi-colored reproduction on a color monitor | Electricity | 44 | Expired |
| US4075662A | Method and system for compensating the non-linearities in a reproduction process | Electricity | 41 | Expired |
| US4561016A | Method and apparatus for recording color pictures for multicolor printing | Electricity | 40 | Expired |
| US4482917A | Method for a reproduction of colored masters in four-color printing using color reduction | Electricity | 38 | Expired |
| US4284996A | Driving ink jet recording elements | Electricity | 38 | Expired |
| US4393399A | Method and apparatus for partial electronic retouching of colors | Electricity | 38 | Expired |
| US4084183A | Method for the electro-optical reproduction of half-tone pictures | Electricity | 36 | Expired |
| US4568984A | Method and apparatus for scanning masters | Electricity | 35 | Expired |
| US4110826A | Apparatus and process for color-identification | Physics | 33 | Expired |
| US4075663A | Method for the rastered reproduction of half-tone pictures providing changes in the individual picture elements during transfer from an original to a reproduction | Electricity | 32 | Expired |
| US4328515A | Method and a device for recorrecting standard color corrections in a color picture recording | Electricity | 32 | Expired |
| US4590515A | Method and apparatus for modifying color reduction depending on tone | Electricity | 31 | Expired |
| US4231069A | Method and apparatus for producing image combinations | Electricity | 30 | Expired |
| US4013829A | Method for the production of printing forms | Electricity | 29 | Expired |
| US3964382A | Engraving device for a printing form engraving machine | Emerging Cross-Sectional Technologies | 29 | Expired |
| US4285009A | Apparatus for producing corrected color chromatic components | Electricity | 28 | Expired |
| US4464677A | Method and circuit arrangement for partial recorrection of color recognition spaces in color recognition | Physics | 28 | Expired |
Source: USPTO / EPO open patent data. Counts and citation impact are objective bibliographic measures.