Dither volume with three thresholds for each cell location

• US 20040046980A1
• Filed: 08/08/2003
• Published: 03/11/2004
• Est. Priority Date: 11/09/1998
• Status: Active Grant

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Lapstun, Paul, Walmsley, Simon Robert
• Granted Patent: US 7,277,205 B2
• Time in Patent Office: Days
• US Class Current: 358/1.9
• CPC Class Codes: B41J 11/008 Controlling printhead for accurately positioning print image on printing material, e.g. with the intention to control the width of margins
• CPC Class Codes: B41J 11/42 Controlling printing material conveyance for accurate alignment of the printing material with the printhead; Print registering
• CPC Class Codes: B41J 13/103 for the sheet feeding section
• CPC Class Codes: B41J 2/0452 reducing demand in current or voltage
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04551 using several operating modes
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/0457 Power supply level being detected or varied
• CPC Class Codes: B41J 2/0458 controlling heads based on heating elements forming bubbles
• CPC Class Codes: B41J 2/04586 controlling heads of a type not covered by groups B41J2/04575 - B41J2/04585, or of an undefined type
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/04596 Non-ejecting pulses
• CPC Class Codes: B41J 2/155 for line printing
• CPC Class Codes: B41J 2/16505 Caps, spittoons or covers for cleaning or preventing drying out
• CPC Class Codes: B41J 2/16511 Constructions for cap positioning B41J2/16547 takes precedence
• CPC Class Codes: B41J 2/16585 for paper-width or non-reciprocating print heads
• CPC Class Codes: B41J 2/175 Ink supply systems ; Circuit parts therefor
• CPC Class Codes: B41J 2/17566 Ink level or ink residue control
• CPC Class Codes: B41J 2/515 line printer type
• CPC Class Codes: B41J 2002/17569 : based on the amount printed or to be printed
• CPC Class Codes: B41J 2202/17 : Readable information on the head
• CPC Class Codes: B41J 2202/20 : Modules
• CPC Class Codes: B41J 2202/21 : Line printing
• CPC Class Codes: B41J 25/34 : Bodily-changeable print heads or carriages
• CPC Class Codes: B41J 29/02 : Framework
• CPC Class Codes: B41J 29/13 : Cases or covers
• CPC Class Codes: B41J 29/38 : Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
• CPC Class Codes: G03G 15/0863 : provided with identifying means or means for storing process- or use parameters, e.g. an electronic memory
• CPC Class Codes: G03G 15/55 : Self-diagnostics; Malfunction or lifetime display
• CPC Class Codes: G03G 2215/0697 : being an electronically readable memory
• CPC Class Codes: G03G 2221/1823 : Cartridges having electronically readable memory
• CPC Class Codes: G06F 3/1213 : at an intermediate node or at the final node
• CPC Class Codes: G06F 3/1214 : at the submitting node
• CPC Class Codes: G06F 3/122 : with regard to computing resources, e.g. memory, CPU
• CPC Class Codes: G06F 3/1247 : by conversion to printer ready format
• CPC Class Codes: G06F 3/1284 : Local printer device
• CPC Class Codes: G06K 15/00 : Arrangements for producing a permanent visual presentation of the output data , e.g. computer output printersprinting or plotting combined with another operation, e.g. with conveying, G06K17/00
• CPC Class Codes: G06K 15/02 : using printers
• CPC Class Codes: G06K 15/102 : using ink jet print heads
• CPC Class Codes: G06K 15/1814 : including print-ready data, i.e. data already matched to the printing process
• CPC Class Codes: G06K 15/1815 : Receiving print data in mixed format
• CPC Class Codes: G06K 15/1817 : Buffers
• CPC Class Codes: G06K 15/1852 : involving combining data of different types
• CPC Class Codes: G06K 15/1855 : Combining raster data and graphic primitives
• CPC Class Codes: G06K 15/1856 : characterized by its workflow
• CPC Class Codes: G06K 15/1857 : involving parallel processing in the same printing apparatus
• CPC Class Codes: G06K 2215/0094 : Colour printing
• CPC Class Codes: H04N 1/32561 : using a programmed control device, e.g. a microprocessor
• CPC Class Codes: H04N 1/32587 : Controller
• CPC Class Codes: H04N 1/32598 : Bus based systems
• CPC Class Codes: H04N 1/3871 : the composed originals being of different kinds, e.g. low- and high-resolution originals
• CPC Class Codes: H04N 1/40 : Picture signal circuits H04N1/387 takes precedence
• CPC Class Codes: H04N 1/41 : Bandwidth or redundancy reduction by scanning H04N1/17 ; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 1/60 : Colour correction or control H04N1/54 takes precedence
• CPC Class Codes: H04N 1/642 : Adapting to different types of images, e.g. characters, graphs, black and white image portions

Abstract

While a general large layer dither volume provides great flexibility in dither cell design, by decoupling different intensity levels, they are inefficient to access since each colour component requires the retrieval of a different bit from the volume. Therefore in a multi threshold dither volume for digital halftoning a contone colour image, in the form of an array of contone colour pixel values to bi-level dots, there is allocated for each dither cell location a fix set of n thresholds defining n+1 intensity intervals within which said dither cell location is defined to be alternatively not set and set.

Claims

1. A dither volume for digital halftoning a contone image, in the form of an array of contone color pixel values, to bi-level dots, said dither volume comprising for each dither cell location, a fixed set of 3 thresholds defining 4 intensity levels within which said dither cell location is defined to be alternately not set and set.

2. A dither volume according to claim 1 wherein each dither cell is split into subcells and stored in separately addressable memories from which said different 3 threshold values are retrieved in parallel.

3. A dither volume according to claim 1 comprising 256 layers.

4. A dither volume according to claim 3 wherein the contone data is dithered using a triple threshold 64×

64×

3×

8-bit.

5. A method of dithering a dither volume, for digital halftoning a contone image, in the form of an array of contone color pixel values, to bi-level dots, comprising the steps of:

assigning for each dither cell location a fixed set of 3 thresholds defining 4 intensity intervals within which said dither cell location is defined to an alternative not set and set.

6. A method of dithering a dither volume according to claim 5, including the steps of dividing each dither cells into subcells, and storing each address of the subcells in separately addressable memories from which said n thresholds are retrieved in parallel.