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Title: Gray Balance - Part 1Submitted By: Catherine HaynesDate Submitted: 04/03/03Author: Catherine Haynes, Manager of Training

Gray Balance - Part 1

Gray balance is a top re!ire"ent for o#erall color balance in the repro$!ction% The threeprocess color in&s - yello', "agenta, an$ cyan - "ost often 'ill not pro$!ce a ne!tral% (or 'illthey al'ays pro$!ce ne!tral light, "e$i!", an$ $ar& grays in screene$ #al!es% )hite light is"a$e !p of e!al parts of re$, green, an$ bl!e light% Blac& is achie#e$ 'hen all three ha#e beenco"pletely absorbe$% The f!ll #al!e range of ne!tral grays that lie bet'een 'hite an$ blac& canbe achie#e$ 'hen balance$ or e!al le#els of each of the three light pri"aries ha#e beenabsorbe$%

Gray balance refers to the ability of the set of process in&s to absorb e!al a"o!nts of the threelight pri"ary colors across the range of light to $ar& 'hen they are pro$!ce$ on the press%*$eally, this "eans that a + $ot #al!e in each process color 'o!l$ pro$!ce a #ery light gray% +0 $ot #al!e in each 'o!l$ pro$!ce a "e$i!" #al!e of gray, etc% *n reality, e!al screens of

process in&s $o not absorb e!al a"o!nts of the pri"ary colors an$ so, 'itho!t correction, $onot pro$!ce a #al!e range of ne!tral grays% They are i"perfect, o!t of balance%

n i"portant aspect of color separation is to a$.!st the screen #al!es or $ot sies to achie#egray balance% *f this balance is not achie#e$ thro!gho!t the possible spectr!" of halftone $ots,the ne!tral grays 'ill be tinte$ yello', re$, or bl!e% *"proper color balance also can ca!se thecolors on the print other than gray to shift% The cyan in& is o#erpo'ere$ by the "agenta an$yello', res!lting in a bro'nish color 'here a ne!tral gray or blac& is $esire$%

 This is controlle$ in color separation by i"balancing the three color printers% The cyan printer isallo'e$ to print larger $ot sies of in& 'hile the "agenta an$ yello' printers are re$!ce$ in $otsie by a controlle$ a"o!nt% correct set of separations 'ill be i"balance$ to pro$!ce ne!tral

#al!es thro!gho!t the #al!e scale fro" highlights to sha$o's% t that point, gray balance isachie#e$%

 The potential ca!ses of i"proper gray balance are n!"ero!s an$ incl!$e al"ost e#ery #ariablein the process color syste"% Color separations often can be bla"e$ for i"proper color balance,not necessarily beca!se they are incorrect, b!t beca!se they !s!ally are a$.!ste$ to therepro$!ction characteristics of another printing process%

 The follo'ing table is an ea"ple of gray balance #al!es for CM2 fro" T5s *67T8% This is .!stan ea"ple% These #al!es 'ill nee$ to be 9g!re$ base$ on the $ot gain, $ensity, color of processin&s, an$ trapping characteristics for each set of printing con$itions% 6!nning a characteriationcan help the prepress s!pplier $eter"ine the best gray balance #al!es for a gi#en set of

con$itions% 6!nning control targets, s!ch as the one reco""en$e$ by *67T also pict!re$belo'8, can help the printer "a&e s!re nothing has change$ in the printing process%

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or "ore infor"ation on this iss!e, please contact; info/0?/03Author: Catherine Haynes, Manager of Training 7er#ices

Gray Balance - Part 2

 The theory of color printing s!ggests that acceptable res!lts can be achie#e$ by !sing the threesecon$ary colors or pri"ary absorbers% This is often tr!e, an$ the a$$ition of a poor blac& printeroften 'ill hin$er "ore than help% The blac&5s p!rpose is t'ofol$% irst, it allo's for a less thanperfect color balance beca!se it contrib!tes to ne!trality in color areas that are slightly o!t ofbalance an$ 'hich sho!l$ be ne!tral% 7econ$, it allo's for a $ar&er sha$o' or contrast, 'hichoften isn5t possible si"ply by o#erprinting the three process colors%

Blac& $oes 'hat cyan, "agenta, an$ yello' $o in$epen$ently, that is it absorbs all of the green,re$, an$ bl!e light that stri&es it% Blac& $oes this all at once, so it can be s!bstit!te$ 'here allthree pri"aries nee$ to be absorbe$% Blac& can be !se$ 'here !ne!al, b!t not necessarily $ar&,colors are nee$e$% 7ince blac& $oes the pri"ary absorption, it can s!bstit!te for the other colors%

or ea"ple, in a section of a print that is epecte$ to repro$!ce a speci9c color on the original,@0 "agenta, A0 cyan, an$ +0 yello' is re!ire$% *f a blac& printer 'ere !se$, the separator'o!l$ ta&e this into acco!nt an$ re$!ce the le#el of the three colors to an e!al a"o!nt an$allo' the blac& to "a&e !p the $ierence to repro$!ce the sa"e $ensity on the print%7!btraction of each of the three color printers fro" ne!tral tones in the repro$!ction an$s!bstit!ting blac& for the" is calle$ !n$er color re"o#al C68% )hen $one correctly, C6

re$!ces the a"o!nt of epensi#e process color in& !se$ an$ increases the less epensi#e blac&in& 'itho!t serio!sly aecting the color !ality of the repro$!ction%

Dften, a s&eleton blac& is !se$% *n this case, only the etre"e $ar& areas of the print recei#eblac& in&% The reality of $ot gain "a&es any gain of the blac& printer three ti"es as tro!bleso"ebeca!se of its absorption in three $ierent 'a#elengths% 7o the restricte$ area of the s&eletonblac& is #ery pop!lar beca!se $ot gain 'ill occ!r only 'here a$$e$ $ensity is re!ire$%

 The T *67T organiation states C6 is not al'ays the best sol!tion for =eographic printing% *tis i"portant to "aintain $e9nition, contrast, an$ sha$o' $etail 'hen !sing !n$er color re"o#al%

Title: Gray Balance - Part 3

Date Submitted: 0?/0>/03Author: Catherine Haynes, Manager of Training 7er#ices

Gray Balance - Part 3Standard Color Separations s! Achromatic Color "Gray Component #emoal $GC#%&

 The stan$ar$ color separation halftone printing process is base$ on the co"bine$ eects ofa$$iti#e an$ s!btracti#e color-"iing principles% *n chro"atic process-color printing, all h!es, as'ell as blac& an$ ne!tral gray, essentially are "a$e 'ith the three basic in&s% Blac& is !se$ tostabilie $ar& gray an$ a$$ $epth to sha$o's as in$icate$ abo#e% )hen three colors areo#erprinte$, the t'o $o"inant ones $eter"ine the color, 'ith the thir$, lesser color contrib!tingto the color printing an$ grayness%

*n recent years, a $ierent approach to process-color printing has ca!ght people5s attention% Thisapproach has been calle$ achro"atic process color or gray co"ponent re"o#al, a"ong other

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ter"s% *n GC6 process color printing, the pri"ary an$ secon$ary colors are the sa"e as inchro"atic printing, b!t blac& replaces the gray co"ponent of the thir$ color% Tertiary colorsE no'are co"pose$ of t'o colors an$ blac&% (o' blac& is the $o"inant color in gray an$ blac&%Mo$ern electronic scanners allo' the !n'ante$ color to be selecti#ely re"o#e$ fro" the yello',"agenta, an$ cyan, an$ a portion of the re"o#e$ color is replace$ by blac& refer to tablebelo'8%

  Chromatic Process GC# Process

Primary Color Space

 2ello', Magenta, Cyan Far&ening is acco"plishe$ 'ithe!al !antities of the other t'opri"ary colors%

Far&ening is acco"plishe$ 'ith blac&%

Secondary Color Space

6e$GreenBl!e

 2ello' Magenta 2ello' CyanMagenta Cyan

 2ello' Magenta 2ello' CyanMagenta Cyan

Tertiary Color Space

Bro'nFar& Bl!eFar& Green

ll 3 basic colors arrange$accor$ing to chro"atic #al!es% T'o pre$o"inant pri"ary colors,one $ar&ening color blac& isso"eti"es a$$e$ for $epth%

 T'o basic colors Blac&Bro'n I yello' "agenta blac&F&% Bl!e I "agenta cyan blac&F&% Green I yello' cyan blac&

Blac' and (eutrals

  Three basic colors in theirrespecti#e percentages 'ith thea$$tion of blac& for $epth%

 Theoretically; blac& onlyCo"ponents of the 3 basic colors,$epen$ing on printing con$itions%

$#antages clai"e$ for GC6 incl!$e sharper printing beca!se all $etail is in the blac&8, better

color consistency, stable gray balance, less sensiti#ity to color-in& =!ct!ations, re$!ce$ in&!sage an$ fe'er trapping proble"s%

Dn the negati#e si$e; this process is !ni!e an$ re!ires a "a.or re-learning of process color forthose !se$ to the chro"atic "etho$% Proofs 'ill be $ierent an$ progressions 'ill be obsolete%

*nter"iing of stan$ar$ an$ chro"atic separations is not a goo$ i$ea% lso, the blac& in& "!stha#e a higher $ensity, "!st be ne!tral an$ "!st gi#e a$e!ate co#erage% Fot-gain control of theblac& printer is essential%

 The T *67T organiation reco""en$s GC6 be restricte$ to a single !n'ante$ color% *67T alsostates GC6 sho!l$ not be !se$ 'hen the printer is printing line blac& an$ process blac& on the

sa"e plate% *n this sit!ation a s&eleton blac& or a short blac&8 "ay be preferre$ to allo' theprinter greater tolerance in setting i"pression%

ETertiary Colors J Those obtaine$ by "iing t'o secon$ary colors%

- o!n$ation of leographic Technical ssociation% leography Principles an$ Practices o!rthK$ition% 6on&on&o"a; o!n$ation of T, 1??+%

C !n$er color a$$ition8 increases the $ot sies of the three process colors in the $ar& ne!tralareas% This co"pensates 'hen the GC6 process re$!ces cyan, "agenta, an$ yello' $ot sies too"!ch% )itho!t C, $ar& areas "ay be lighter than $esire$% Dn the other han$, C6 !n$er colorre"o#al8 "ay be !se$ to co"pensate for this sa"e iss!e%

- Miles 7o!th'orth an$ Fonna 7o!th'orth% Color 7eparation Dn The Fes&top% Li#onia; Graphicrts P!blishing, 1??3%

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