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___Colour

RGB & CMYKColour Space / HalftonesRick Black / Tints & Backgrounds

___Pre-Print

Spell Check / Printer MarksPre Flight Checks / Mock-UpsClient Sign Off / Proofs

060810

121416

ColourC

MYK

& R

GB

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Colour

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___CMYK

CMYK is the colour mode that is used for colour print and it’s reffered to as a subtractive colour process. CMYK refers to the inks used which are Cyan, Magenta, Yellow and Key, which means Black. The ink is typically applied seperatly in the order of the abreviation and colours are mixed to make the full available spectrum. ‘Key’ is called this because it refers to the printing plates used having to be ‘keyed’ or alligned with the black plate. In additive color models such as RGB, white is the “additive” combination of all primary colored lights, while black is the absence of light. In the CMYK model, it is the opposite: white is the natural color of the paper or other background, while black results from a full combination of colored inks.

___RGB

The RGB colour mode is made from red, green and blue lights and is used for on-screen. It’s referred to as an additive colour process. RGB is the default colour mode of Photoshop. An image from a digital camera or scanner will be RGB. It has a broader spectrum of colours available for use on screen as appose to CMYK for print. The range is called the ‘colour gamut’ and the RGB gamut is greater than CMYK as you can see on the diagram to the left. The inner shape is CMYK and the outer shape is RGB.

When you convert the image from RGB to CMYK, the brightness of the colour may be altered if it isn’t in the CMYK gamut to the nearest colours available.

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Col

ours

Spa

ce &

Hal

ftone

s

___Colour Space

Most desktop scanners, digital cameras, and video capture systems save files as RGB and the conversion of RGB files to CMYK can be done in many ways.

RGB converts to only CMY directly. However, when printing, we must add black ink and in doing so must cut back on some color. The Undercolor Removal (UCR) setup will help control this ratio so that a maximum ink density for the four colors will be 300% when printing on a coated paper stock.

___Halftones

In offset lithography, the density of CMYK inks can not be varied in continuous fashion across an image, so a range is produced by means of halftoning.

In halftoning, translucent CMYK ink dots of variable size are printed in overlapping grids. Grids are placed at different angles for each of the ink colors. Smaller halftone dots absorb less light; thus, as a result of an increase in the amount of reflected light, apparent density is decreased and the object appears lighter.

___Monotone

A Monotone is greyscale image with a spot colour overprinted which accents the grey scales within the greyscale image. This only works with greyscale images.

___Duotone

A Duotone is the same process as a monotone but using two spot colours overlayed to pick up highlight and shadows in the image giving it a more ‘colour’ like quality. Hence the name ‘Duo’ ‘Tone’.

Colour

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___G

reys

cale

Hal

ftone

___C

MYK

Hal

ftone

___M

onto

ne__

_Duo

tone

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CMYK value refers to a set of 4 numbers between one and 100 representing the amount of each color mixed in order to achieve the desired color.

The initial guess from this information would be that K=100 would be solid black but this is far from the truth. In actual fact, this creates a dark grey. To make RICH black. CMYK adds bits of cyan, magenta and yellow to make the key darker in order to achieve rich black.

It is important however to not use RICH black for small text for obvious reasons. CMY and K are printed in slightly separate positions overlapping which will make small body copy appear blurred when printed.

Ric

h B

lack

, Tin

ts &

Bac

kgro

unds

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___Tints & Backgrounds

If you wish to reproduce a large solid black background I would recommend that the black prints at 100 per cent, along with a 40 per cent cyan tint to provide more density. This is often referred to as a “shiner”, and produces what is sometimes called a “rich black”.

The inclusion of a common colour background or strap heading across several pages of a feature or sections of a magazine can draw attention to the natural minor variations in colour balance that occur across a press/presses and during a press run. This can be minimised by creating these common colours out of as few process colours as possible. Give careful consideration to the use of one, or perhaps two colours to produce the common colour.

Such a colour will enable a more consistent reproduction than the same object defined using all four process colours. However, certain two-colour combinations can also be prone to unattractive colour shifts - particularly when both colour values are midtones. Two-colour combinations where one colour is considerably higher than the other prove more stable, producing a more consistent, balanced result.

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Spel

l Che

ck &

Prin

ter M

arks

Spell Checking before you send your work off is one of the most important pre-print checks to complete. Doing this can settle any later problems resulting in having to re-print which also saves you or the company paying out a lot of money. It also allows for less stress when pointing the blame through problems like this.

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____Trim Marks

These are small lines which show exactly where the finished

page will be cut during the finishing

process. They should display at the edge of

each margin.

____Colour Bars

Colour bars are printed outside the

trim area and are used for quality

control purposes. Squares of colour are printed on the

area of the page to be trimmed off, which

the printing press operator uses to

check colour density and consistency is

maintained. This checking process is automated by some printers, with digital

scanners tracking the colour bars to

ensure quality and consistency

is maintained.

____Registration Marks

The little circle with a cross through is printed using every colour of the four-colour

printing process. If they’re being

printed accurately, they should overlap

precisely so the mark looks entirely black. Therefore if any of the colours are slightly offset

(out of register) then they’ll be displayed,

showing the job isn’t being printed

correctly.

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Pre

Flig

ht C

heck

s &

Moc

k U

ps

Pre-flighting is a term used in the printing industry to describe the process of confirming that the digital files required for the printing process are all present, valid, correctly formatted, and of the desired type. The term originates from the pre-flight checklist used by pilots.

The process of preflighting a print job helps reduce the likelihood of rasterization problems that cause production delays. Page layout software applications automate portions of the pre-flight process.

Typically, client provided materials are verified by a pre-flight operator for completeness and to confirm the incoming materials meet the production requirements.

__Common Checks

- embedded images and graphics are embedded and accessable.

- Fonts are not corrupt, accesable and correct format.

- images are in correct format, colour format and resolution. colour profiles are included and are not corrupt.

- colour seperations are correct.

- confirm that the page layout document size, margins, bleeds, marks and page information all fit within constraints.

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A mockup is a prototype if it provides at least part of the functionality of a system and enables testing of a design.

Mock-ups are used by designers so they can see the design in printed format. This means that it is much easier to pick out any mistakes that would probably go un-noticed on screen.

Mock-ups address the idea captured in a popular engineering one-liner:

“You can fix it now on the drafting board with an eraser or you can fix it later on the construction site with a sledge hammer.”

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Spec

ial I

nks

Getting sign-off, in writing, is a vital part of best practice when sending designs, copy or code to clients. If changes need to be made later then, with sign-off completed, it is the client’s responsibility — not yours. If, for example, there is a typo in a design for a flyer (perhaps the date is wrong!) and the client spots the mistake *after* printing 1000s of copies the responsibility for the cost of re-printing is the clients… not yours.

It is well established in law that by signing-off artwork the client accepts final responsibility for it. It means that, under normal circumstances, re-printing becomes a client’s responsibility once your artwork has been approved.

Observing best practice in the design and marketing business means obtaining sign-off from your client before artwork goes into production.

Once the client has signed off the artwork you are no longer responsible for it. It means that your Professional Indemnity insurance will not meet a claim for reprint (for example), because it would be the client’s responsibility (or possibly the printer’s if the reprint was the result of a straightforward printing error).

If, however, a client tried to blame you and attempted to make a claim against you, even if you weren’t at fault, then your Professional Indemnity would defend you. This would also be the case if the client simply refused to pay you, and threatened to counterclaim if you pursued the debt.

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___Pre-press

A prepress proof uses ink jets, dyes, overlays or other methods to simulate the final printed piece.

___Press

A press proof uses the printing plates and inks specified for the job.

Proofing your work comes at various stages but there are specific types of proofs created during prepress and printing that allow the designer to see if their piece will come out as intended in the final printing. Different types of printing proofs are more accurate than others but with increased accuracy comes increased costs.

Printing proofs are used for checking that all text and graphics and coluors come out as expected before going to press. It is a good practice to print a proof from your desktop printer and send along with your digital files to your service bureau or commercial printer. They can be black and white or in color but a good PostScript laser proof is ideal. If the file won’t print properly to a desktop printer, chances are it won’t come out on the printer press correctly either.

____Design By

Sam Lanesadcastle.co.uk

@sadcastle

____Typefaces Used

RaisonneHelvetica