Image processing apparatus especially suitable for producing smooth-edged output multi-level tone data having fewer levels than input multi-level tone data

Claim 2

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said the pixel, so that output image data is output to a printer; and control means for adjusting an exposure time of the printer in accordance with predetermined characteristic relationship between the exposure time and a dot intensity, thus allowing a value of intensity of each dot of the output image output to the printer to be proportional to an intensity of said two successive pixels supplied by said multilevel data means; wherein each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means.

Claim 3

An image processing apparatus according to claim 1, wherein said multilevel data means includes a memory for storing a data conversion table, said data conversion table defining each said multilevel tone data in accordance with an address value corresponding to a value of each pixel of said input image data input by said scanner.

Claim 4

An image processing apparatus according to claim 1, further comprising error data means for adding a weighted error data to each pixel of said input image data, said weighted error data corresponding to a difference between a value of each said pixel and a predetermined threshold value.

Claim 5

An image processing apparatus according to claim 3, wherein said multilevel data means includes a memory for storing a data conversion table, said weighted error data being defined in said data conversion table stored in said memory in accordance with a difference between a value of each said pixel of said input image data and a predetermined threshold value.

Claim 6

An image processing apparatus according to claim 1, further comprising edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two-pixel processing means to the printer or outputting said image data of said multilevel data means to the printer, in accordance with said pixel of said image data being detected by said edge detection means.

Claim 7

An image processing apparatus according to claim 5, wherein said selection means outputs said output image data of said two-pixel processing means to the printer when said edge detection means detects that said pixel of said image data is not an edge of the input image, and said selection means outputting said image data of said multilevel data means to the printer when said edge detection means detects that said pixel of said image data is an edge of the input image.

Claim 8

An image processing apparatus according to claim 5, further comprising line smoothing means for supplying image data having pixels indicating a smooth line to said edge detection means, said pixels of said image data being generated by obtaining an average value from values of a given number of successive pixels of said input image data in a main scanning line of said scanner.

Claim 9

An image processing apparatus comprising a scanner for inputting image data indicative of an image with a multilevel tone: multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value Of said one pixel, so that output image data is output to a printer; control means for adjusting an exposure time of the printer in accordance with predetermined characteristic relationship between the exposure time and a dot intensity, thus allowing a value of intensity of each dot of the output image output to the printer is proportional to an intensity of said two successive pixels supplied by said multilevel data means; and error data means for adding a weighted error data to each pixel of said input image data, said weighted error data corresponding to a difference between a value of each said pixel and a predetermined threshold value; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; said multilevel data means includes a memory for storing a data conversion table, said weighted error data being defined in said data conversion table stored in said memory in accordance with a difference between a value of each said pixel of said input image data and a predetermined threshold value; and said control means includes a memory means for temporarily storing a value of a preceding pixel of said two successive pixels, allowing said control means to convert each value of said multilevel tone data into an image data value by every two pixel data in accordance with said data conversion table stored in said memory.

Claim 10

An image processing apparatus comprising a scanner for inputting image data indicative of an image with a multilevel tone: multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value Of said one pixel, so that output image data is output to a printer; control means for adjusting an exposure time of the printer in accordance with predetermined characteristic relationship between the exposure time and a dot intensity, thus allowing a value of intensity of each dot of the output image output to the printer is proportional to an intensity of said two successive pixels supplied by said multilevel data means; and error data means for adding a weighted error data to each pixel of said input image data, said weighted error data corresponding to a difference between a value of each said pixel and a predetermined threshold value; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; said multilevel data means includes a memory for storing a data conversion table, said weighted error data being defined in said data conversion table stored in said memory in accordance with a difference between a value of each said pixel of said input image data and a predetermined threshold value; and said control means includes a memory means for temporarily storing a value of a preceding pixel of said two successive pixels, allowing said control means to convert each value of said multilevel tone data into an image data value by every two pixel data in accordance with said data conversion table stored in said memory.

Claim 11

The apparatus according to claim 8, wherein said two-pixel processing means carries out a two-pixel process in which a value being converted from a preceding pixel of said two successive pixels is greater than a value converted from a following pixel of said two successive pixels.

Claim 12

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means: two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; and edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two-pixel processing means to the printer, in accordance with said pixel of said image data being detected by said edge detection means; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and said edge detection means includes means for detecting a front-side edge of the input image with relation to a main scanning line of said scanner.

Claim 13

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means: two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; and edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two-pixel processing means to the printer, in accordance with said pixel of said image data being detected by said edge detection means; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and said edge detection means includes means for detecting a front-side edge of the input image with relation to a main scanning line of said scanner.

Claim 14

An image processing apparatus according to claim 10, further comprising dilatation means for outputting a signal at high level to said selection means for a first time period when said edge detection means detects that said given number of said successive pixels include an edge of the input image, said first time period needed to supply values of said successive pixels of said input image data to said selection means being longer than a time period needed to supply values of two successive pixels of said input image data to said selection means.

Claim 15

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; and edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two pixel processing means to the printer, in accordance with said pixel of said image data being detected by said edge detection means; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and said edge detection means includes a gray-level difference detecting part for detecting a difference in gray level between two values of preceding and following pixels spaced apart by a prescribed distance along a main scanning line, said preceding and following pixels being selected from among a given number of successive pixels of the input image data in the main scanning line, said edge detection means thus detecting whether or not a pixel of said input image data is an edge of the input image in accordance with said gray level difference detected by said gray-level difference detecting part.

Claim 16

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; and edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two pixel processing means to the printer, in accordance with said pixel of said image data being detected by said edge detection means; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and said edge detection means includes a gray-level difference detecting part for detecting a difference in gray level between two values of preceding and following pixels spaced apart by a prescribed distance along a main scanning line, said preceding and following pixels being selected from among a given number of successive pixels of the input image data in the main scanning line, said edge detection means thus detecting whether or not a pixel of said input image data is an edge of the input image in accordance with said gray level difference detected by said gray-level difference detecting part.

Claim 17

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two-pixel processing means to the printer, in accordance with said pixel of said image data being detected by said edge detection means; and line smoothing means for supplying image data having pixels indicating a smooth line to said edge detection means, said pixels of said image data being generated by obtaining an average value from values of a given number of successive pixels of said input image data in a main scanning line of said scanner; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and said selection means includes means for outputting said output image data of said two-pixel processing means to the printer when said edge detection means detects that said given number of said successive pixels do not include an edge of the input image, and for outputting said image data of said multilevel data means to the printer when said edge detection means detects that said given number of said successive pixels include an edge of the input image.

Claim 18

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; edge detection means for detecting whether or not a pixel of said image data supplied by said scanner is an edge of an input image, and selection means for selectively outputting said output image data of said two-pixel processing means to the printer, in accordance with said pixel of said image data being detected by said edge detection means; and line smoothing means for supplying image data having pixels indicating a smooth line to said edge detection means, said pixels of said image data being generated by obtaining an average value from values of a given number of successive pixels of said input image data in a main scanning line of said scanner; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and said selection means includes means for outputting said output image data of said two-pixel processing means to the printer when said edge detection means detects that said given number of said successive pixels do not include an edge of the input image, and for outputting said image data of said multilevel data means to the printer when said edge detection means detects that said given number of said successive pixels include an edge of the input image.

Claim 19

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; and two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and when said output image data is supplied by said two-pixel processing means to said printer, an output image having pixels to which multilevel tone data described with "N"gray levels is assigned to be printed out by said printer.

Claim 20

An image processing apparatus comprising: a scanner for inputting image data indicative of an image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output by said multilevel data means; and two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated by said two-pixel processing means; and when said output image data is supplied by said two-pixel processing means to said printer, an output image having pixels to which multilevel tone data described with "N"gray levels is assigned to be printed out by said printer.

Claim 21

An image processing apparatus comprising: a scanner for inputting image data indicative image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output said multilevel data means; and two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated said two-pixel processing means; and when said first value of said one pixel is equal to 50 percent of said value of said one pixel stored in said storage means, said second values of said two successive pixels are generated by said two-pixel processing means using said first value.

Claim 22

An image processing apparatus comprising: a scanner for inputting image data indicative image with a multilevel tone; multilevel data means for generating multilevel tone data from said input image data using a prescribed error diffusion process, said multilevel data means including means for outputting image data having pixels to which said multilevel tone data is assigned; storage means for temporarily storing a value of one of two successive pixels included in said image data output said multilevel data means; and two-pixel processing means for converting said value of said one pixel stored in said storage means into a first value, and for generating second values of said two successive pixels using said first value of said one pixel, so that output image data is output to a printer; wherein: each pixel of said output image data is described by said second values of said two successive pixels generated said two-pixel processing means; and when said first value of said one pixel is equal to 50 percent of said value of said one pixel stored in said storage means, said second values of said two successive pixels are generated by said two-pixel processing means using said first value.