Multi-tone image processing method and apparatus

Abstract

A multi-tone image processing method and apparatus in which mutually dissimilar tone levels are realized by changing the additive condition of recording energy by means of different recording positions, even when the number of recording operations within a specific range is identical. For example, in an electrophotographic apparatus, when the number of irradiation by a light spot within a specific range remains constant as the irradiation position is changed in the specific range, there is a change in the additive condition of the optical energy within said specific range. Thus, the area rendered visible within the aforesaid specific range also changes, thereby changing the tone level.

1. A multi-tone image processing method comprising:
 receiving a plurality of image data wherein each image data represents a tone level;    specifying a pattern from a plurality of patterns stored in a memory in response to each of said image data, each of said plurality of patterns defining a number of recording operations and positions of recording operations within a specific range;    wherein each pattern represents a specific tone level and wherein different tone levels may include a same number of recording operations at different positions within the specific range; and    generating recording data for executing recording operations by reviewing the pattern specified for each image data.    
     
     
       2. A multi-tone image processing method as claimed in  claim 1 , wherein all of the recording operations are of substantially the same intensity. 
     
     
       3. A multi-tone image processing method as claimed in  claim 1 , wherein more than one tone level includes the same number of recording operations at different positions. 
     
     
       4. A multi-tone image processing apparatus for receiving multi-tone image data representing a tone level of a multi-tone image and generating recording data based on the multi-tone image data, comprising:
 a memory which stores a plurality of patterns corresponding to a plurality of tone levels, respectively, each of said plurality of patterns defining a number of recording operations and positions of recording operations within a specific range, at least two of said plurality of patterns being identical in the number of recording operations but different in the positions of recording operations within said specific range for different tone levels; and    a control unit which specifies one of said plurality of patterns stored in said memory in response to the multi-tone image data and generates recording data by reviewing the specified pattern.    
     
     
       5. A multi-tone image processing apparatus as claimed in  claim 4 , wherein each of said plurality of patterns is constituted by a matrix in which each element of an m*m square matrix is divided into k segments in a row direction. 
     
     
       6. A multi-tone image processing apparatus as claimed in  claim 4 , wherein all of the recording operations are of substantially the same intensity. 
     
     
       7. A multi-tone image processing apparatus as claimed in  claim 4 , wherein each of said plurality of patterns is constituted by an m*n matrix. 
     
     
       8. A multi-tone image processing apparatus as claimed in  claim 7 , wherein the value of each cell of the m*n matrix is binary. 
     
     
       9. A multi-tone image processing apparatus as claimed in  claim 7 , wherein the value of each cell of the m*n matrix is ternary or greater. 
     
     
       10. A multi-tone image recording apparatus for recording a multi-tone image based on multi-tone image data representing a tone level of a multi-tone image, comprising:
 converting means for converting multi-tone image data into recording data so that at least two tone levels are realized by differentiating positions of recording dots within a specific range while a number of the recording dots remains constant within said specific range; and    a recording system which receives the recording data and produces the recording dots based on the recording data.    
     
     
       11. A multi-tone image recording apparatus as claimed in  claim 10 , wherein said converting means includes a memory which stores a plurality of patterns corresponding to a plurality of tone levels, respectively, each of said plurality of patterns defining the number of the recording dots and the positions of the recording dots within said specific range. 
     
     
       12. A multi-tone image recording apparatus as claimed in  claim 10 , wherein said recording system includes a photosensitive member, an optical system which irradiates the photosensitive member by a light spot, and a developing device which develops areas irradiated by the light spot with developer. 
     
     
       13. A multi-tone image processing method as claimed in  claim 10 , wherein all of the recording dots are of substantially the same intensity. 
     
     
       14. A multi-tone image recording apparatus as claimed in  claim 11 , wherein each of said plurality of patterns is constituted by an m*n matrix of which each cell corresponds to the recording dot. 
     
     
       15. A multi-tone image recording apparatus as claimed in  claim 14 , wherein the adjacent recording dots in a row direction of the matrix are produced continuously while the adjacent recording dots in a column direction of the matrix are produced discretely with a spatial interval. 
     
     
       16. A multi-tone image recording apparatus as claimed in  claim 15 , wherein the recording dots are produced by pulse width modulation in the row direction of the matrix. 
     
     
       17. A multi-tone image recording apparatus comprising:
 a photosensitive member which moves in a sub-scanning direction;  
 a laser optical system which selectively generates a laser beam and scans said photosensitive member with a spot of the laser beam in a main scanning direction substantially perpendicular to said sub-scanning direction;  
 a developing device which develops areas irradiated by the spot of the laser beam with developer;  
 a memory which stores a plurality of exposure patterns corresponding to a plurality of tone levels, respectively, each of said plurality of exposure patterns defining a number of irradiation by the spot of the laser beam and the positions of the irradiation within a specific range, at least two of said plurality of exposure patterns being identical in the number of the irradiation but different in the positions of the irradiation within said specific range for realizing different tone levels, wherein a size of the area developed by the developing device within said specific range is different for each tone level;  
 a controller which receives multi-tone image data representing a tone level of a multi-tone image and specifies one of said plurality of exposure patterns in response to the multi-tone image data; and  
 a driver which drives said laser optical system to control generation of the laser beam by reviewing the exposure pattern specified by said controller.  
 
     
     
       18. A multi-tone image recording apparatus as claimed in  claim 17 , wherein each of said plurality of exposure patterns is constituted by an m*n matrix of which each cell corresponds to the irradiation by the spot of the laser beam. 
     
     
       19. A multi-tone image recording apparatus as claimed in  claim 17 , wherein generation of the laser beam is controlled by pulse width modulation in the main scanning direction. 
     
     
       20. A multi-tone image processing method as claimed in  claim 17 , wherein all of the irradiations are of substantially the same intensity. 
     
     
       21. A multi-tone image recording apparatus as claimed in  claim 17 , wherein said laser optical system includes a semiconductor laser. 
     
     
       22. A multi-tone image recording apparatus as claimed in  claim 21 , wherein said driver switches on and off the semiconductor laser in correspondence with the exposure pattern specified by said controller. 
     
     
       23. A multi-level image recording apparatus as claimed in  claim 22 , wherein said driver controls the intensity of the laser beam between three or more levels. 
     
     
       24. A multi-tone image processing method comprising:
 receiving a plurality of image data wherein each image data represents a tone level;  
 specifying a pattern from a plurality of patterns, each of said plurality of patterns defining a number of recording operations and positions of recording operations within a specific range, wherein each pattern represents a specific tone level and at least one of the patterns has a larger number of recording operations than another of the patterns that represents a lighter  darker tone level within the specific range; and  
 generating recording data for executing recording operations by reviewing the pattern specified for each image data.  
 
     
     
       25. A multi-tone image processing method, comprising:
 receiving a plurality of image-data, wherein each image data represents a tone level;    specifying a pattern of black and white picture elements from a plurality of patterns, each of said plurality of patterns defining a number of recording operations all of which have substantially the same intensity and positions of the recording operations within a specific range, wherein each of said patterns represents a specific tone level and wherein at least one of the patterns includes a white picture element in a position that includes a black picture element in another of the patterns representing a lighter tone level; and    generating recording data for executing recording operations by reviewing the pattern specified for each image data.    
     
     
       26. A multi-tone image processing method, comprising:
 receiving a plurality of image-data, wherein each image data represents a tone level;    specifying a pattern of black and white picture elements from a plurality of patterns, each of said plurality of patterns defining a number of recording operations and positions of recording operations within a specific range, wherein each of said patterns represents a specific tone level and wherein at least one of the patterns includes a white picture element in a position that includes a black picture element in another of the patterns representing a lighter tone level, wherein the another pattern and the at least one pattern have the same number of recording operations; and    generating recording data for executing recording operations by reviewing the pattern specified for each image data.    
     
     
       27. A multi-tone image processing method as claimed in  claim 26 , wherein all of the recording operations are of substantially the same intensity. 
     
     
       28. A multi-tone image processing method comprising:
 receiving a plurality of image data wherein each image data represents a tone level;    specifying a pattern of black and white picture elements from a plurality of patterns, each of said plurality of patterns defining a number of recording operations and positions of the recording operations within a specific range, wherein each of said patterns represents a specific tone level and wherein at least one of the patterns includes a white picture element in a position that includes a black picture element in another of the patterns representing a lighter tone level; and    generating recording data for executing recording operations by reviewing the pattern specified for each image data, wherein said recording operations are executed by a photo emitter which emits a beam having a characteristic in which an energy level is greater in a center portion of said beam than in a remaining portion of said beam.    
     
     
       29. A multi- tone image processing apparatus for converting multi - tone image data representing a tone level of a multi - tone image to binary image data, said apparatus comprising:      a memory which stores a plurality of patterns representing a plurality of tone levels, respectively, each of said plurality of patterns having effective cells and non - effective cells and defining a number of effective cells and positions of effective cells within a specific range, wherein at least one of the patterns has a larger number of effective cells than another of the patterns that represents a darker tone level within the specific range; and        a converter which specifies one of said plurality of patterns stored in said memory according to the tone level of the multi - tone image data to be converted and converts the multi - tone image data to the binary image data based on the specified pattern.     
     
     
       30. A multi- tone image processing apparatus as claimed in    claim 29   , wherein each of said plurality of patterns is constituted by a matrix in which each element of an m*m square matrix is divided into k cells in a row directions.   
     
     
       31. A multi- tone image recording apparatus comprising:      a memory which stores a plurality of patterns representing a plurality of tone levels, respectively, each of said plurality of patterns having effective cells and non - effective cells and defining a number of effective cells and positions of effective cells within a specific range, wherein at least one of the patterns has a larger number of effective cells than another of the patterns that represents a darker tone level within the specific range;        a converter which specifies one of said plurality of patterns stored in said memory according to the tone level of the multi - tone image data to be converted and converts the multi - tone image data to the binary image data based on the specified pattern; and        a printer which prints the image according to the binary image data converted by said converter.     
     
     
       32. A multi- tone image recording apparatus as claimed in    claim 31   , wherein said converter includes an X - address counter, a Y - address counter and a Z - address counter, said Z - address counter specifying one of said patterns in the memory, and the X - address counter and the Y - address counter specifying one of said cells of the specified pattern according to horizontal and vertical printing operations of said printer.   
     
     
       33. A multi- tone image recording apparatus as claimed in    claim 31   , wherein said printer includes a light source which emits a light beam, a driver which drives said light source based on the binary image data, an image carrier which moves in a vertical direction, and a deflector which deflects said light beam in a horizontal direction and scans said image carrier to form an image on said image carrier.   
     
     
       34. A multi- tone image recording apparatus as claimed in    claim 33   , wherein said converter includes an X - address counter, a Y - address counter and a Z - address counter, said Z - address counter specifying one of said patterns in the memory, and the X - address counter and the Y - address counter specifying one of said cells of the specified pattern according to horizontal and vertical scanning operations of said printer.   
     
     
       35. A multi- tone image recording apparatus for recording an image based on multi - tone image data representing tone levels on an image, said recording apparatus comprising:      a converter which converts multi - tone image data into recording data so that at least two tone levels are realized by differentiating positions of recording dots within a specific range while a lighter tone level has a larger number of recording dots than a darker tone level within the specific range; and        a printer which receives the recording data from said converter and records the recording dots based on the recording data.     
     
     
       36. A multi- tone image recording apparatus as claimed in    claim 35   , wherein said printer includes a light source which emits a light beam, a driver which drives said light source based on the recording data, an image carrier which moves in a vertical direction, and a deflector which deflects said light beam in a horizontal direction and scans said image carrier to form an image on said image carrier.   
     
     
       37. A multi- tone image recording apparatus as claimed in    claim 17   , wherein said size of the area developed by the developing device within said specific range varies depending upon the number of adjacent irradiations continuing in the main scanning direction within said specific range.   
     
     
       38. A multi- tone image recording apparatus as claimed in    claim 17   , wherein said size of the are a developed by the developing device within said specific range varies depending upon the number of adjacent irradiations continuing in the main scanning direction or the sub - scanning direction within said specific range.