[Mass noun] 2. The provision of something for consideration, inspection, or use.
The production processes used in graphic design and the printing industry, to physically put ink on paper, can be harnessed many ways to produce creative results. These may include manipulating the colour channels and printing plates, overprinting or reversing out and changing the order in which colours print. The impact and creative potential of a design can be enhanced when you control
the creative process, rather than letting it control you, as the following pages will show.
Raster s& Vecto rs Raster (photographs) and vectors (illustrations) are the mainstay image format of printed material today. A raster file can be converted into a vector file for graphic effect. A raster image does not contain sufficient information to produce a clear image when enlarged, as pixelation begins to occur. A vector image is made up of paths, each with a mathematical formula that tells the path how it is shaped and what colour it is bordered with or filled by.
Donâ€™t forget! A poor quality raster image is still an image that does not contain enough information to be reproduced clearly. Rasters are turned into vectors for creative effect, not to solve resolution issues. Raster Image
16 Colour Vector image
Shade of Grey Vector
Black & White Vector
Raster s Pros
Raster images are capable of displaying a myriad of colours in a single image and allow for colour editing beyond that of a vector image. Raster images can display finer nuances in light and shading at the right resolution.
Raster images cannot be made larger without sacrificing quality. Raster images are often quite large files.
Vecto rs Pros
Vector images are scalable, so that the same image can be designed once and resized infinitely for any size application â€“ from business card to billboard to logo. Vectors display at the highest resolution allowed by the output device Vector images are relatively lightweight.
Vector images cannot display the natural qualities of photographs.
CMYK These are the standard process colour in the order that they print; Cyan, Magenta, Yellow and Black.
Chann els & Plates
It is neither practical or economical to mix up ink and print every individual colour to be found in a piece of artwork or colour photograph, so another method has to be used. The secondary colours Cyan, Magenta and Yellow, and Key (also known as black) are the colours used by printers to reproduce full-colour work in CMYK.
The four process inks are applied via separate printing plate in the cyan, magenta, yellow and black sequence in order to build up an image. Notice the difference in addition of the black plate (K), makes to the image (bottom right) compared to the C+M+Y version (bottom left). C
Print Order The order in which each of the CMYK process colours prints has an impact on the resultant printed design. Logically, only a colour that has already been printed can be â€˜overprintedâ€™ with another colour. In standard printing, magenta follows cyan, therefore can overprint yellow, magenta or cyan. When using a varnish you also need to consider whether the special finish will overprint or knockout. Understanding this concept requires more than simply knowing the order that with which to print the plates or screens in. Knowledge of the print order is fundamental for understanding overprinting techniques.
square, the cyan square must first be printed with a white circle (A). The hole in which the circle will print is slightly smaller than the magenta circle to be printed to avoid ink trapping issues (B). The magenta circle slightly overprints the blue square to avoid any white lines appearing due to a misalignment of the two plates(C).
Knockout A knockout is a gap that is left in the bottom ink layer so that an image printed over it (which overlaps it), appears without colour modification from the ink underneath it. The bottom colour is literally â€˜knocked-outâ€™ of the area where the other colour overlaps it. To print a magenta circle on a cyan
Ink Trapping Ink trapping is the overlapping of areas of coloured text or shapes to compensate for mis-registration on the printing press. Ink trapping is required because the halftone dots that make up the printed images overlap (because they are different sizes and at different screen angles); therefore, the colours must also be overlapped to prevent the appearance of white gaps where they are supposed to meet.
g Over Printin By default, when you print opaque, overlapping colors, the top color knocks out the area underneath. Overprinting prevents knockouts and makes the topmost overlapping printing ink appear transparent in relation to the underlying ink. As a general rule, printers do not like to have flat colours overlapping, because it slows down the rate of drying of the inks and introduces the possibility of smudging. A colour will change shade, too, when printed over another one .
Overprint An overprint describes the printing of one colour on top of another.
Surprint A surprint is where a percentage or a tone of a colour is used.
Reverse A reverse out is where the white (or colour) of the page or substrate is used and the printed colour forms that background or base colour.
Half tone is a continuous tone image converted to line by turning it into a pattern of dots, either digitally, by laser, or by photographing it through it through screen. Although, you will most likely know a halftone image digitally. A series of screens containing halftone dots are used to replicate the continuous photographic tones in the print process. Once printed, these dots gives the illusion of full-colour image.
This is the base image.
This images uses a halftone effect using dots to replicate the image.
The use of halftone lines produces a graphic effect.
Rather, than dots, this halftone image is produced from squares.
Screen Angles When printing in two colours, for example black and any other process or special colour, each will be sent at different angles. The black will be screened at 45 degrees, as this angles is the least obvious to the human eye and black is the strongest colour, and the second colour will be screened at 75 degrees. This principle follows all the way to the four colour printing, and indeed, if a fifth colour is added, it will be given an alternative screen angle to the four colours.
Each of the four process colours has standard screen angles (black 45 degrees, magenta 75 degrees, yellow 90 degrees and cyan 105 degrees). The use of different angles prevents screen interference and the development of moire patterns, and results in clear colours and the ability to reproduce a four colour images. Yellow 90 Cyan 105
Moire Pattern A moire pattern occurs when the dots of two screens interfere, creating what is referred to as a basket-weave pattern.
80% 70% 60% 50% 40% 20%
Colour reproduction is usually achieved by screening the three trichromatic process colour; cyan, magenta and yellow, in increments of 10%. This produces 1,330 available tints for the designer to use, and this increases to almost 15, 000 when black is included as well.
Tints A tint is a shade of colour that has been diluted, through the addition of white, in order to create a paler variation of it.
Donâ€™t Forget! The use of non-white substrates can produce colour variation and give the illusion that several colour have been incorporated so be careful when choosing the substrate for the job. Below: (left Image) 50% tint of black & cyan, (Right) 50% of black.
Below: (left Image) 10% tint of black & cyan, (Right) 10% of black.
s Tonal Image Duotone A halftone cannot always reproduce the full tonal range of a photograph. A duotone is superimposition of a contrast black halftone over one-colour half tone, which is shot for highlights and middle tones, using the same image. The most commonly used colours are yellows, browns, and reds. The intention is to create a rich range of colours, and at the same time add coloured tint to the result. For high quality work, where cost is no constraint, a duotone may even comprise two printings in black, or in black with a shade of grey.
A tonal image is akin to a black-and-white photograph in which the white tone have been replaced by one of, or a combination of, the other CMY process colours. This is a basic duotone image produced using cyan and black.
This is a duotone image using yellow, which produces a warm, soft result.
This is a tritone image using red and yellow.
This quadtone image produces a greater contrast and shadow depth.
Published on Dec 12, 2013