ACTAGRA• PHJOURNAL FOR PRINTING SCIENCE AND

ACTA GRAPH. 18(2006)1-4, 1- 40

Contents

Research papers

Environmental data on gravure and offset printing

M. Enroth M. Johansson

A projection of automated bookproduction control 1M. Barisic

Studies of Ink Trapping IllDirect detection of small air bubbles in ink layer 1

/. Naito/ Y. Tsuzah A. Ohto/ Y. Nitta

Multicolor graphic picture withoriginal ring raster element 2;. Ziljak Vujic

Environment protectionEdited by Z Bolanca 3

News 3

Papers published in Acta Graphica journal have been reviewed by two independent experts

). ZIL)AK VU)IC: MULTICOLOR GRAPHIC PICTURE WITH ....., ACTA GRAPH. 1 8( 2006)1- 4, 25 -29 25

ACTA GRAPH. 170 UDC 655.2:778.18:004.9Research paper

Received: 10-11-2005Accepted: 27-06-2006

Multicolor graphic picture with original ring raster element

Jana Ziljak Vujic

Author

jana Ziljak Vujic, M. Sc., Senior lecturer at the Technical CollegeKonavoska 2, Hr-7 0000 Zagreb, Croatia

E-mail: janazv@tvz.hr

Abstract

This paper deals with graphics and color rastering using new raster forms as well as raster combinations in vector anda pixel graphics, with combining both graphics in the same document. The unwanted increase or decrease of color coverage depends most of all on the fringe volume length bordering the raster element. The idea of this research work is to find a form alters in the least extent the raster element fringe volume in respect to its increase or decrease. The innovation in this research work is not only in the fact that the raster element's volume is altered in the minimal degree, but also that it does not change at all with the covering capacity increase or decrease. The solution led in the direction of creating such a raster element that has at least two independent shells where one increases in size together with the raster element increase, and the other one decreases when the raster element size increases. We have named this raster form as the ring form due to its similarity with a classical smooth ring.

Key words

Dot gain, Ring rastering, PostScript.

1. The graphic raster problem

Reproduction of graphic works of art by means of print is carried out with the help of rastering. Raster element forms have been the following: round dot, rhomb and line because they could be produced by optomechanical methods. In this paper the terms raster element or raster dot apply to every raster element regardless of their being in

the form of a round dot, ellipse, square, line or

The raster dot is situated inside an area named as the raster cell. For single color printing imitating grayness, the raster cell contains a white and black surface by means of which one has the impression of grayness depending on the covering ratio. This black surface represents the black dot.

The term dot gain is also linked with the raster

26 ). Zll)AK VU)IC: MULTICOLOR GRAPHIC PICTURE WITH ....., ACTA GRAPH. 18 ( 2006 ) 1-4, 25-

and white surface ratio may appear when carrying out the printed form production and printing. Widening and narrowing of the raster dot depend on the production material: colors, toners, inks, paper and processes such as: intoxicating quality, narrowing. These parameters have a different performance for each different printing technique. This problem is not as great in printing with low lineature, whereas it is quite prominent when high lineatures and large black areas are concerned.

By combining different raster forms in multicolor printing we are approaching a new experimental chapter in reproduction photography, and hereby

graphic art produced in this manner is becoming real challenge in the graphic design of securities.

2. Modeling of the ring raster element

Mathematical methods are applied successfully a open up new areas in carrying out individualiz design tasks. The first step is in creating t mathematical relation in three-dimensional form the standard unit cell required by the PostScr interpreter for carrying out the rastering wi printing techniques. The ratio that includes tfringe conditions of unit space follows:

in printing as well. The special visual quality of Z = Abs[Sin[Sqrt[(xA2+yA2) )*L)), for positive.

Picture 7 - Ring raster form with coverage from the ring center towards the cell center and fringe.

And Z=Abs[l - Sin[Sqrt[(xA2+yA2) ]*L] ], for negativ

Picture 2- Ring raster with negative filling and simultaneous coverage advancing from the center and fringes

Definition in PostScript:{ dup mul exch dup mul add sqrt Lmul sin abs } bind def

that in the executive part takes two pieces of data from the memory stack top representing the micro position of the x and y resolution of the exposure unit in building the raster element.

dup mul exch x2 dup mul y2add x2+y2

The raster element in the proposed ring form h the external (r 2 ) and interior (r1 ) fringe with tw different values.

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The expanding of the raster cell covering capacity enhances the external volume, and equally diminishes the internal circle volume. This results in the conclusion that the sum of the raster elements volume is always equal and does not depend on the raster cell covering capacity. Color waste, enhancing or diminishing is most oftenlinked with the raster element volume.

In the auxiliary program named Ring all the instructions are given on basis of original PostScript commands (*6). Parameter L is an exception and has the value of L=120 for this ring form. It is possible to design vector concentrated rings with parameter Las parts of a raster dot. The executive program solution was tested for vector and pixel graphics. Thelineature is given as 5 to 45 lines per centimeter.

------a------ ---------a---------

0=2r;]f+ 2r2lf r2=.!!.- r,

20=2r;]f+ 2 (- r,)lf

r 1 0=2r,lf+ alf- 2r,lf

0 =alf

Picture 3 - Independence of the raster element volume and the blackening

5

95 85 75 6510

55 45 35 25 15 5

Picture 4 - Ring raster. It is discussed in this paper in terms of positive and negative

5

95 85 75 65 5510

45 35 25 15 5

Picture 5 - The negative ring raster element for L= 120 forms a duality of circular and sharp structures for greater covering ca pacity

o.

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As the original program is also enclosed hereto, it is possible to use it and test many other applications.

Color solutions have been tested for both types of pixel and vector graphics. In all cases they behave well when they are printed on digital printing unitsand on photo units for high quality results.

3. Multicolor portrait rastering with a ring raster

Four color printing was carried out on a portr in pixel graphics having a very low lineature order to see the raster dot with the naked eye.

/a 3 def /b 30 def 20 20 translate/kut 45 def /lin 5 def /sivo 1 def lin kut {prsten} bind setscreen

By rastering individual images with the help of designed raster dot we are carrying out a vecomplex graphic task where the result is t

200 {0 0 moveta a b akvir siva setgray

production of very attractive pieces of graphic a

2 0 translate /siva siva 0.005 sub def The secret lies in the fact that by using rast

fill } repeat -400 40 translateelements such as, for instance, the triang

/kut 35 def /lin 15 def /siva 0 def/kut 25 def /lin 25 def /sivo 1 def

(Typography 03 *5), square, circle in carrying o the image rastering we have as a result

/kut 15 def /lin 35 def /siva 0 def

completely new picture- graphic work of art. Ne

rastering forms give a fair image interpretation,Program 6: Continuous blackening program with angle and lineature change for ring raster elements.

graphic work of art in fact. If it is well designed, may reach a high artistic level.

Picture 6 - Continuous blackening with angle and lineature chanee for ring raster elements

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Picture 7- Color rosets with ring raster

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4. Conclusion and scientific contribution within a unit space bordering the raster form. Up til now it has been assumed that such form does no

The scientific contribution is the new raster form that provides independence of the raster element

exist even theoretically, so that additional researchwork was carried out only to minimalize the rati

volume and the blackening in the dot gain area of between blackening and the raster element volumereproduction photography research. An outline is The results of this work have been carried outgiven tested through the Mathematica program in tested and with this goal in mind a minima3D and 20 visualization of fringe conditions set by PostScript rastering. Such form has been reached by finding the ratio that has two shells in20 and is possible in the PostScript interpretation

5. References

PostScript program has been attached that makes i possible to prove the assertions put forward in thi paper. At the same time it may be used as a basis fo further investigation of raster cell form.

[1] Geofrey Brett, Digital Prepress Technologies, ISBN 185802 261 4, Pira International Lt.

2000. [2] Kelvin Tritton, Stochastic Screening, Pira International, ISBN 1 85802 126 x, UK.

1996.

[3] V. Ziljak, K. Pap, PostScript, Zagreb, FS, 1999,/2003. ISBN 953-199-00-X, UDK: 681.3.06;655.26

[4] Tiskarstvo 03, Zbornik radova, ur. Mladen Lovrecek, grupa autora, FS I Graficki fakultet, 2004. ISBN 953-199-016-6, UDK: 655 (082) 655;004.92>(082)

[5] Tiskarstvo 04, Zbornik radova, ur. Mladen Lovrecek, grupa autora, FS I Graficki fakultet, 2005. ISBN 953-199-019-0: UDK 655(082), 655:004.92>(082),655.4:004.738.5>(082)

[6] j. Ziljak, K. Pap, V. Ziljak, Forming a Presonal Handwriting for UNICOD, Procedings of the 5th international Design conference, Editor D. Marjenovic, Dubrovnik, 1998.

[7] j. Ziljak, Visual identity of Design 2000, Procedings of the 6th international Design conference, Editor D. Marjanovic, Dubrovnik, 2000.

[8] J. Ziljak, Visual identity of Design 2000, Procedings of the 6th international Design conference, Editor D. Marjanovic, Dubrovnik, 2000.

[8] j. Ziljak, I. Ziljak, Elaboration of the design of the rater elements on securitie, Procedings of the 6th international Design conference, Editor D. Marjanovic, Dubrovnik, 2002.

[1 0] j. Ziljak, V. Vancina, D. Agic, I. Ziljak, K. Pap, UK. 1996. New screeningElements in multi-colour printing for special purposes, 30th international Research Conference of IARIAGI, Dubrovnik, 2003.

[11] I. Ziljak, j. Ziljak Vujic, Elaboration of design of screening elements,8th International Design Conference Design 2004.

[12] Stephen Wolfram, Mathematica/1991.-2005 . ISBN =-201-515077. WolframResearch, Addison- Wesley Publishing CoRedwood City, Ca