Source: http://www.google.com/patents/US5339171?dq=7,546,338
Timestamp: 2017-12-16 00:37:37
Document Index: 326254689

Matched Legal Cases: ['art 103', 'art 102', 'art 202', 'art 202', 'art 202', 'art 104', 'art 202', 'art 204', 'art 204', 'art 103', 'art 104', 'art 103', 'art 104']

Patent US5339171 - Image processing apparatus especially suitable for producing smooth-edged ... - Google Patents
An image processing apparatus includes a scanner for inputting image data indicative of an image with a multilevel tone, a multilevel data part for generating multilevel tone data from the input image data through a prescribed error diffusion process, the multilevel data part outputting image data having...http://www.google.com/patents/US5339171?utm_source=gb-gplus-sharePatent US5339171 - Image processing apparatus especially suitable for producing smooth-edged output multi-level tone data having fewer levels than input multi-level tone data
Publication number US5339171 A
Application number US 07/893,094
Publication number 07893094, 893094, US 5339171 A, US 5339171A, US-A-5339171, US5339171 A, US5339171A
Inventors Tetsuo Fujisawa, Yukio Sakano
Patent Citations (8), Non-Patent Citations (2), Referenced by (56), Classifications (8), Legal Events (4)
Image processing apparatus especially suitable for producing smooth-edged output multi-level tone data having fewer levels than input multi-level tone data
US 5339171 A
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.
2. 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.
8. An image processing apparatus comprising
a scanner for inputting image data indicative of an image with a multilevel tone:
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;
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.
9. 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.
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;
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.
11. 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.
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;
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.
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;
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.
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
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.
a scanner for inputting image data indicative image with a multilevel tone;
storage means for temporarily storing a value of one of two successive pixels included in said image data output said multilevel data means; and
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.
FIG. 6 shows the construction of the multilevel error diffusion part 103 of the image processing apparatus of FIG. 3. An adder 201 performs addition of an error data G1 to a 7-bit image data SD supplied by the gamma correction part 102 so as to correct image data, and outputs the corrected data SD+G1 to a read only memory ROM 202 which is coupled to the adder 201. The ROM 202 includes a multilevel rendition part 202a and an error determining part 202b, and it must have a storage capacity that can contain approximately 8 bit ×256. After a 8-bit address data which is the corrected data SD+G1 output by the adder 201 is received, a 3-bit image data ID1 is supplied by the multilevel rendition part 202a of the ROM 202 to the two-pixel processing part 104, and a 5-bit error data G2 is supplied by the error determining part 202b thereof to an error buffer memory 203 and to a diffusion matrix making part 204. The error data G2 supplied to the error buffer memory 203 (and to the diffusion matrix making part 204) is used in the subsequent image processing. A data conversion table, as shown in FIG. 7, is stored in the ROM 202 in accordance with the correspondence between the input address data value (SD+G1), the conversion data value (ID1) and the error data value (G2). As 5-level rendition of pixels of the image data is used in this embodiment, the value of 3-bit image data ID1 ranges from 0 to 4, and the value of 5-bit error data ranges from 0 to 31.
(Dot Density)=0.17×ID×0.06
Referring to FIG. 15, a description will be given of a case in which a 9-level image data (0 to 8) is produced by the multilevel error diffusion part 103. A multilevel image data ID2 is supplied by the multilevel rendition part of the ROM 202 to the two-pixel processing part 104. The ROM 202 must have a storage capacity of approximately 8 bits ×256 of address data plus corresponding conversion data in this embodiment. Also, in this embodiment, a 9-level rendition of pixels of the image data is carried out, and the value of the 4-bit image data ID2 after the multilevel error diffusion process ranges from 0 to 8. This image data is supplied by the part 103 to the part 104.
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U.S. Classification 358/3.03, 358/406, 382/252
Cooperative Classification H04N1/4057, H04N1/4056
European Classification H04N1/405C4, H04N1/405C2
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:FUJISAWA, TETSUO;SAKANO, YUKIO;REEL/FRAME:006196/0477