In my second book (2/2) the content will be Colour and Costing, followed by some art work that relates to both books.
The computers native colour space and the system for capturing and displaying colour images electronically. All TV, computer and electronic display screens create color by generating red, green and blue lights. Our eyes are sensitive to red, green and blue, and our brain mixes the colours together . For screen display, red, green and blue subpixels (dots) are energized to the appropriate intensity. When all three subpixels are turned on high, white is produced. As intensities are equally lowered, shades of gray are derived. The base color of the screen appears when all subpixels are turned off. For printing on paper, the CMYK color space is used, not RGB. Combinations of cyan, magenta, yellow and black ink make up the colors. White is typically derived by using white paper and no ink for those areas; however, if white is of critical importance, a white spot color can be added to the CMYK process. See CMYK and spot colour.
As mentioned on the last page, the CMYK system is used for printing. For mixing of pigments, it is better to use the secondary colours,since they mix subtractively instead of additively. The secondary colours of light are cyan, magenta and yellow, which correspond to the primary colours of pigment (blue, red and yellow). In addition, although black could be obtained by mixing these threein equal proportions, in four-colour printing it always has its own ink. This gives the CMYK model. The K stands for 'Key' or 'blacK', so as not to cause confusion with the B in RGB. In additive color models such as RGB, white is the additive combination of all primary coloured lights, while black is the absence of light. In CMYK, it is the opposite. White is the natural colour of the paper or background, while black results from a combination of coloured inks. When saving money on ink, and producing deeper black tones, unsaturated and dark colours are produced by using black ink instead of the combination of cyan, magenta and yellow.
Design tools like scanners, monitors, software applications and printing processes all work with different colour spaces. It is these colour spaces that will define the range or colour, or in this case the gamut of colours. Using colours at the fringes of the gamut will mean it is difficult to ensure that they stay the same when swapping from one device to another. In the diagram above, the red line represents Hexachrome gamut, the blue line represents the RGB gamut. The outer black line denotes the spectral colour gamut. RGB displays approximately 70% of the colours perceived by the human eye, And CMYK even less. The six-colour Hexachrome process adds orange and green and this serves to increase the gamut.
Halftone images use used in newspapers and magazines because it is a much more efficient way to print images. Since a halftone image is made up of discreet dots, it requires significantly less ink to print than a continuous tone image. As long as the resolution of the image (measured in LPI) is high enough, the dots appear as a continuous image to the human eye. However, if you closely examine the images printed in a newspaper, you should be able to see the dots that make up the halftone image.
A halftone image is made up of a series of dots rather than a continuous tone. These dots can be different sizes, different colours, and sometimes even different shapes. Larger dots are used to represent darker, more dense areas of the image, while smaller dots are used for lighter areas.
INKS
Offset Inks
Most people when purchasing inks never seem to give ink a second thought when thinking about what colours they want to go with. Its a good idea to know what ink suits what paper to get the most out of your print.
High Gloss
This ink includes a high content of varnish to accomplish maximum sheen. This ink is most effective when used on coasted and cast-coated stocks. However, high gloss is not appropriate for heat during as this can reduce a glossy finish.Heat set
Quick drying inks that are used in web offsets. These ink solvent are vaporised as they pass through a heating cahmber at the end of the press. Once is has gone through this heating chamber, it is then sent through cooling rollers that allows the ink to set.
Metallic
Metalic ink is a mixture of metal dust and varnish. Metallic inks have a greate effect when printed on coated paper as they have a tendency to rub off ink that has been laid down thickly.
Soy Based
These inks are made with a hight amount of soy bean oil rather than petroluem that is included with most other inks. Soy based inks give you a saturated colour and a solid coverage. These inks do happen to be more expensive than other inks and may requirea longer time to aloow to dry.
Fluoresent
This ink is much more vibrent and attracive than standard inks, this ink can also be mixed with other process inks to increae thier look. Fluresent inks unfortunantly don’t keep their glow as long as standard inks do. This means this ink may not be suitable for peices that are expected to have a long life or peices that may be exposed to sunlight.
Varnishes & Protective Liquid Coatings
These varnishes and liquid coatings are applied to a piece of work to protect the inked surface, they can also be applied to make the finish better. There is a whole range of different techniques with each one giving its own advantage. It so happens that these varnishes and coatings work best on coated paper. This is because the ink is absorbed better with this stock than any other, created a fresher finish.
Spot Varnish
A clear coating is applied on press or in line. Spot varnish is the same as any other ink when it comes the price. It comes in gloss or de-saturated and can also be tinted with other inks. It is also used to enhance photographs or other images that may be lacking effect. One problem is it doesn’t offer that much protection against muck or spills, there is some protection against finger prints. When applied to metal inks, spot varnish can prevent flaking and rub-off.
Aqueous coating
This is a glossy coating made from a mix of polymers and water that is usually applied the publication like magazines to protect them against damage. These coatings are applies as a flood varnish. A flood varnish means the whole sheet is covered, meaning everything is protected. This type of coating requires a special coating unit that is installed at the end of a press.
Ultraviolet or UV coating
This process involves a plastic liquid and offers much more protection and a higher degree of gloss than aqueous coating. Not many printers can apply this to a piece, it is more likely to be used in screen printing or spot varnish with a roller. By doing this with a roller you find it is more economical as you can do long runs whereas screen printing is more cost effective. When you are applying UV coatings, make sure to use wax free ink. UV coating is available in a dull finish it happens to still be more expensive than gloss. This process of printing is mostly seen on books, folders and table tents. Its hard plastic surface just so happens to be quite week and can crack at the fold lines, so, extra care should be taken when folding.
A gradient, is a colour fill that gradually blends from one colour to another. A gradient can contain more than two colours, all fading smoothly from one colour to the next. Gradients are very useful for creating shading for three-dimensional and metallic effects. Most graphics software allows you to create a variety of gradient effects such as linear, radial, and angle. Some software even offers gradient mesh effects, which allows you to create elaborate shading by plotting colours to each of the intersections of an imaginary mesh, so that the colours all blend together.
even offers gradient mesh effects, which allows you to create elaborate shading by plotting colours to each of the intersections of an imaginary mesh, so that the colours all blend together.
This scheme, sometimes called monotonal, uses just one colour, and one colour only, with little variation in value or saturation. Lighter and darker variations on the colour are not part of the overall scheme, nor are duller or brighter variations of that colour.
Simply a process for producing halftone illustrations using two shades of a single colour or black and a colour When printing, its a method of printing an illustration either in a dark and a tinted shade of the same colour or in two different colours from two plates of a monochrome, original made from negatives at different screen angles.
Spot Colour
Spot colours are used to highlight certain parts of a print, whether it be a logo, a headline or decorative design as they tend to stand/pop out and are Mostly used in Offset litho printing. In contrast to 4-print process(CMYK), spot colours are custom pre-mixed inks, they are opaque and therefore do not overprint well. Overprinting being when you print over existing ink.
Spot colours are specified by colour matching systems, the most commonly used of them being the Pantone Matching System(PMS).
The method of printing with Spot colours can be both expensive and cheap. If the product goes to print which has been made to use the 4-print process plus one or more spot colours the price is going to increase. However, it is possible to print products with just one or two spot colours therefore making it generally cheaper than using 4-process printing.
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