STEP-BY-STEP APPROACH TO 

DIGITAL COLOUR SEPARATION

By Nwaelehia, Uzor JN

This is a way of taking to distinctive four components of conventional (Primary) colours that make a particular spectrum of colours of an Artwork, into their different states. The four colour are acronymized as CMYK. The C denotes Cyan which represents the whole variety of blue colours spectrum in an Artwork. M denotes Magenta, which represents the whole of red colours in a picture. Y denotes yellow; this is just a constant colour that does not have combination and again K denoting black which is also on its own, no other colour that joins to form black.  This makes possible for the combination of colours by the machine operators to produce exactly the picture or photograph in the graphical work as an output. Before this three stages will be passed through. 

(1) Photographic Editing (2) Graphic Designs and (3) Lithography, all these stages will join in the perfect production of an image that would appear exactly like the original image. This is one of the PREPRESS stages, which enable PRESS work and at last move to POSTPRESS.

Workstation

PREPRESS

Before a separation job is carried out, the job to be separated must be put together into its designed shape and arranged graphically. The outcome of the arrangement is called Artwork. Artworks could be the arrangement (designed) in any graphical environment including CorelDraw, Photoshop, Corel Photo-paint and so forth. The preferred environment among all other graphic environments is CorelDraw software; this is so because of the enhancement involved that enables vectors and bitmap arrangement into CMYK components. 

Artwork

In this stage, the nature of job is made known, required photographs or pictures are gathered, the expected and a befitting colour choice is also made, the size was taken, manuscripts of write-ups are also assembled and words are typeset and arranged with lines if need be, to form a good and attractive design which is the artwork. The coloration and fonts (character sizes) are chosen and well positioned. It should be noted that other effects could be done outside CorelDraw environment and imported for final touches in CorelDraw. It should be noted that the spaces in between each Word, lines, pictures and bullets matter a lot in a design. They form what is at last known as good graphics which is the artwork to be used in the press. 

Artwork being typesetted for design

Convert To Curve

Before the final Artwork is sent out to the bureau or PRESS, lots of modalities are ensured. The texts in the finished Artwork are converted to curve. This is to ensure that they don't change when taken to another computer of a different number of fonts. If it is not converted and accessed by another personal computer and it happens that the system lacks some fonts, it will definitely change to the ones in that system, thereby scattering the Artwork. That makes it imperative that every Artwork that must be opened by another computer in the bureau should be converted to curve, not bitmap. If converted to bitmap, they form one ungroupable and indivisible image, which will, of course, is inseparable. Therefore it will be full colour including the black that supposed be one colour. The black will appear in the four colours.

Save the Artwork

The Artwork must be saved (stored) in a device like a disc, flash or memory cards that must be accessible at the point it is being received. Before saving into the device, one has to ensure that the whole texts (Characters) are converted to curve and grouped if designed in CorelDraw environment. This would avoid the issue of the fonts in the artwork scattering. The conversion should be done once not twice by depressing Ctrl (control) and the letter Q. if converted the characters go as far as blunting, where there is letter O the whole in it would be covered, thereby changing the desired designed. So convert before saving into the device to be used.

Editing of the Photograph

When this is done, the photographs are especially exported to JPEG, JPG, FFT or TTF among others to reduce the weight and some complications that would be involved.  After which CorelDraw and others could be used all through for the prepress and press work but must favourably, other editing software is used to make the photographs smooth and richly enhanced. Photoshop, Adobe photo deluxe, 2D cool to mention but a few are also used. In this case, the photograph is cropped (removed from the background, enhance by removing stains, scratches, patches, and colour variations equalised to ensure that the image is real and fine.

Doming and Laying

When it gets to this stage, it means, it is done and ready for separation. Since the job is the graphically arrangement as a single page job like A6, A5, A4, A3, A2, A1 or A0. But if it is needed many in one page, it needs to be laid accordingly. Multiple page work, it is expected of the graphics or separator to ensure that it is laid appropriately to the desire of the owner. Bookwork is numbered and arranged in a unique way to ensure accuracy. It must be finally done in A2 or A1 page. The number that the job is placed up to on the page makes the name. If it is two; that is 2ups, 3ups, 4ups, 5ups, 6ups, 7ups, 8ups and so on, according to the page size to be laid on.

The following is to be upheld:

1.    One should get a sheet of paper representing the size of paper to be used by the operator at the final printing stage and fold them into the number of places you would want it to be and write from 1 to the end of the page number you have.

2.    In the laying, first laid two on a single page for as a bookwork that which is even numbers should be placed at the left side of a landscape paper orientation, while the odd numbers are placed on the right-hand side of the printable area, in twos till the end of the pages. A job of 20 pages will be laid; 20 left - 1 right. The reversed could be the case when page 1 will back the cover front, instead of starting on a fresh page.

3.    If A6, it will be laid two in A5, if A5 it will be laid two A5 in one A4, two A4 in A3, two A3 in A2 and two A2 in A1.

4.    Where A6 is needed many as single face page like handbill is needed in A2 especially or in A1 which is very rare; it will be 16A6. If A5, it will be 8A5, if A4 is 4A4, if A3 it is 2A3 in A2 and 2A2 in A1 as the case may be.

5.    If the single page has back as turn over the leaf, the owner will equally specify how it should be laid. If he or she needs 5 plates of A2 for the job, let's assume that the back is one colour since the front is full which 4 colours are but if the owner wants all in the 4 plates then, the orientation would be portrait. While the full-colour side is laid at the bottom, the back would be turned 180 degrees (upside down) to ensure that when printed, it will fall on each other correctly.

6.    In the same vein, if one colour which is otherwise called spot colour is to be laid on A2, the specification would be made, so that they would back each other so that the number will be serial without the problem.

Check That Texts Are Right

Endeavour to edit the texts colour because texts copied from word processing software most times are in RGB of which in full colour. RGB means Red Green and Blue instead of CMYK, which is Cyan Magenta Yellow Black If in that RGB where R:0, B:0 B:0, sometimes in varied RGB where R:41, G:12, B:17 or thereabout. Sometimes, the texts come in CMYK black where C: 100, M: 100, Y: 100, K: 100, which means they will fall four times. This will subject the operator to be so careful and will be wasteful of the papers and mother materials because of the tininess of the texts that falls together into a spot for four times. 

Again, texts copied from word processing environments like Microsoft Word, Word Pad, Microsoft Excel, and Memo Pad among others and pasted directly into CorelDraw, most times as corrupt bitmap that once you turn it 180 degrees, the texts reverse it and scattered in such a way that no one can ever read it. What you need to do is converting first before turning it.

After these are ratified, making sure that the texts are direct black (one colour black), be rest assured that you are set to do separation stage.

How about Photos

At this point in time, one must ensure that all is well as you give so you get back, which expressed as garbage-in-garbage-out. The photos and all bitmap images are alright, none of them are turned upside or half. Sometimes, if the artwork is grouped and turned 180 degrees, bitmaps with transparent effects are halved (divided into half), one side white and the other coloured. They need to be reconverted to bitmap before turning 180 degrees.

Separation Proper

After all, remember the following Sectors; Workstation, RIP Station, the Imagesetter and processor. These are the three sectors that must be passed through before the image is outputted, and processed out dried on the film.  

Imagesetter and Processing Machine

Works Station:

If you have known these sectors, the next is what is: 

a)    This is the first sector where you do your primary design, editing and arrangements are done. At this point, usually, we count many personal computers on the desks doing the preparation. Ready artworks are converted to CMYK bitmaps with text overprinted. The texts must be overprinted to ensure that they fall once and without the hole that would be filled by incoming texts. 

b)    The second stage after exporting it to TIFF, JPG, JPEG, and others, you preview to size; A6, A5, A4, A3, A2, or A1 and go to separation and do the following.

If the machine is ECRM Knockout:

1    Choose the printer

2    Choose paper size

3    Click separation in the print dialogue box

4    Highlight Print Separations

5    Highlight use advanced settings

6    Highlight always overprint black

7    Highlight auto spreading

8    In postscript highlight compatibility

9    In the max point per curve, Highlight auto increase flatness, auto increase fountain steps, optimise fountain fills

10    In Screen Frequency Column, choose 200 lip which is the highest.

When you have done all needed, click preview and apply to see the position. If none cuts and or out of the margins, then print. It either prints or sends the print printout in that would be in a file format directly to the RIP online. Then, you are now needed to rip off the jobs and do the page setup appropriately and enable to go into the recorder and a last you cut and advance into the processing machine to process it.

Check Your Film and Chemical

When the film is exhausted the machine will for sure alert you with 3 times beeps, then you open the top door and load the role of film, close, and press the button to expose media. Exposing media will allow for the areas on the film that has seen light to be pushed forward as to avoid been recorded on those spots. 

Developer and Fixer

Mix chemicals if they are weak. The Developer, anytime it is weak it will no longer be very dark when processed, so you have to change.  In the case of the Fixer; when weak it will show whitish things on the film when processed out and there must be water in the container must be changed to at every 2 weeks because it must be dirty. The chemicals are mixed 1:2 litres ratio. The 5 litres must go with 15 to 20 litre of water in the two chemicals.

PRESS AND POSPTRESS

Once the film is out and cut to their sizes, it could be taken to Lithographer who put them on their separate plates; Cyan for plate 1, Magenta plate 2, Yellow plate 3 and Black plate 4.  Then the PRESS proceeds through the use of Kord, Lord, MOV, Speedmaster as the case may be, to continue the process of Offset Printing where each of the 4 plates of CMYK will be merged together in their correct colours, spot-to-spot, dot-to-dot to form the true images in the original artwork. Thereafter, it proceeds to POSTPRESS where it would be cut or trim to sizes, collated, finished and delivered.

Kord Machine

I hope you must have been enriched by this detailed lecture via www.4clicksblog.blogspot.com Research Group where the Head of this Group is a key participator in Separation industry and more is yet to come your way, in other fields.