Notes about Graphic Design
Notes of: AMBROSE, Gavin; HARRIS, Paul. The Production Manual: A Graphic Design Handbook. AVA Publishing: Switzerland, 2008
Design basics
Measurements
Absolute measurements are measurements of fixed values. For example, a millimeter is a precisely defined increment within a centimeter. Equally, points and picas, the basic typographic measurements, have fixed values, such as the 48pt text above. All absolute measurements are expressed in finite terms that cannot be altered.
In typography, many measurements, such as character spacing, are linked to type size, which means that their relationships are defined by a series of relative measurements. Ems and ens, for example, are relative measurements that have no prescribed, absolute size. Their size is relative to the size of type that is being set.
The em: The em is a relative unit of measurement, used in typesetting to define basic spacing functions. It is linked to the size of the type so that if the type size increases, so does the size of the em, i.e. the em of 72pt type is 72 points and the em of 36pt type is 36 points. The em defines elements such as paragraph indents and spacing.
The en: An en is a unit of relative measurement equal to half of one em. In 72pt type, for example, an en would be 36 points. Although the names em and en imply a relationship to the width of the capital ‘M’ and ’N’, in reality they are completely unrelated, as the illustrations above demonstrate.
The em dash and en dash: An en dash is half an em dash and a hyphen is one third of an em dash, and so it is smaller than an en dash. The size of all these dashes is relative to the type being set. An en dash is used to denote nested clauses, but it can also be used to mean ‘to’ in phrases such as 10–11 and 1975–1981. Em dashes are sometimes used to denote pauses in speech and hyphens are used in hyphenated words, for example, ‘halftone’.
The pica: A pica is a unit of measurement equal to 12 points and is commonly used for measuring lines of type. There are six picas (or 72 points) in an inch (25.4 millimeters). This is the same for both a traditional pica and a modern PostScript pica. There are six PostScript picas to an inch.
Layout
The active and passive areas of a design: Within a layout, a designer has a great deal of freedom about where to place the different design elements. However, due to the way in which the human eye scans an image or a body of text, certain areas of a page are ‘hotter’ or more active, while others will be more passive or periphery. Designers can use this knowledge to help focus attention on an item, or to hide it away. The human eye tends to start processing the information on a page from the top left corner, before moving to the right and then descending the page.
Elements
Image types
Rasters: A raster image is any that is composed of pixels in a grid, where each pixel contains color information for the reproduction of the image, such as the continuous tone photograph in the example below. Rasters have a fixed resolution, which means that an enlargement of the image results in a quality decrease, as shown in the detail. Raster images are usually saved as TIFF or JPEG file formats for print, or JPEG or GIF file formats for use on the web.
Vectors: A vector image contains many scalable objects that are defined by mathematical formulae or paths rather than pixels. Vectors are therefore scalable and resolution independent. As shown below, because vectors are path-based, they can be enlarged infinitely yet remain crisp and clear. Vector files must be saved as EPS formats to retain their scalability. They are used for corporate logos and other graphics, as they are easily portable and cannot be altered from within desktop publishing programs.
Color
Hue, or color, refers to the unique characteristic of a color that helps us visually distinguish one color from another. Hues or colors are formed by different wavelengths of light.
Saturation or chroma refers to the purity of a color, and saturation levels describe a color’s tendency to move towards or away from gray.
Brightness or value refers to how light or dark a color is. Changes in the brightness value can be achieved by mixing a color with black or white.
Neutral gray: a color that is used to allow a designer to more accurately see the balance of colors in an image by providing a neutral base contract. Neutral gray is made from 50 per cent cyan, 40 per cent magenta and 40 per cent yellow, which in the RGB color space is 128 red, 128 green and 128 blue.