Selective screening method

• US 20050030561A1
• Filed: 08/27/2003
• Published: 02/10/2005
• Est. Priority Date: 02/05/1990
• Status: Active Grant

• Current Assignee: Kodak Limited (Eastman Kodak Company)
• Original Assignee: CREO Company Limited
• Inventors: Spiegel, Ehud, Carlebach, Ephraim A., Bronstein, Rafail
• Granted Patent: US 7,130,079 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: G06F 17/15 Correlation function computation including computation of convolution operations arithmetic circuits for sum of products per se, e.g. multiply-accumulators G06F7/5443; digital filters, e.g. FIR, IIR, adaptive filters H03H17/00
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: G06K 2215/0037 depending on an output condition, e.g. size, resolution
• CPC Class Codes: G06K 2215/0094 Colour printing
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: H04N 1/52 Circuits or arrangements for halftone screening
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

An integrated computerized system for use in color printing having at least one digital representation of a color characteristic of at least one page to be printed and a digital storage memory for storing the digital representation. An imposition apparatus is connected to the storage memory to receive the digital representation and arrange the digital representation in accordance with a desired plate layout, thereby to define a plate image. A press set-up device extracts from the plate image the color characteristic and provides ink flow set-up data to a printing press in accordance with the extracted color characteristic.

Claims

1. A method of automatically selecting screen characteristics values to be used for printing a color image, comprising the steps of:

forming a digital representation of said color image, said digital representation comprising a plurality of separations;

dividing at least one said plurality of separations into a plurality of regions; and

assigning at least one screen characteristic value to each said plurality of regions.

2. The method of claim 1, wherein said step of dividing comprises creating a plurality of equal-sized regions.

3. The method of claim 1, wherein said step of dividing comprises creating a plurality of low color-variation regions.

4. The method of claim 1 wherein said step of assigning comprises, for each said plurality of regions, the steps of:

computing said at least one screen characteristic value for each pixel in said region;

finding the most frequent screen characteristic value computed for said pixels in said region; and

assigning said most frequent screen characteristic value to each one of said pixels in said region.

5. The method of claim 4, wherein said step of computing comprises computing a function of the lowest density component of said pixel value.

6. The method of claim 1, wherein said at least one screen characteristic is chosen from the group consisting of a screen angle and a screen dot shape.

7. A method of creating a halftone image of a color image, comprising the steps of:

forming a digital representation of said color image, said digital representation comprising a plurality of separations;

dividing at least one said plurality of separations into a plurality of regions;

assigning at least one screen characteristic value to each said plurality of regions;

providing a screen generator;

providing image data streams to said screen generator, each said image data stream spanning at least one of said plurality of regions, said image data streams additionally comprising said at least one screen characteristic value assigned to each of said plurality of regions spanned by said data stream and a pixel count for each of said regions within said data stream; and

using said provided data streams to create a halftone image of said color image.

8. The method of claim 7, additionally comprising the steps of:

providing an imaging device, wherein each said data streams represents an imaging line of said imaging device; and

imaging said halftone image on said imaging device.

9. The method of claim 8, wherein said imaging device is a film imagesetter.

10. The method of claim 8, wherein said imaging device is a platesetter.

11. The method of claim 8, wherein said imaging device is a proofing device.