HA1 - Technical File – Raster and Vector Images There are two kinds of computer graphics - raster (composed of pixels) and vector (composed of paths). Raster images are more commonly called bitmap images. A bitmap image uses a grid of individual pixels where each pixel can be a different colour or shade. Bitmaps are composed of pixels. Vector graphics use mathematical relationships between points and the paths connecting them to describe an image. Vector graphics are composed of paths. Raster Vector The larger you display a bitmap, the more jagged it appears, while a vector image remains smooth at any size. The jagged appearance of bitmap images can be partially overcome with the use of "anti-aliasing". Anti-aliasing is the application of subtle transitions in the pixels along the edges of images to minimize the jagged effect . A scalable vector image will always appear smooth . Anti-Aliased Bitmap Image: Smooth Vector Image:
Bitmap images require higher resolutions and anti-aliasing for a smooth appearance. Vector-based graphics on the other hand are mathematically described and appear smooth at any size or resolution. Bitmaps are best used for photographs and images with subtle shading. Graphics best suited for the vector format are page layout, type, line art or illustrations.
HA1 - Technical File – Antialiasing Anti-Aliasing is a method of fooling the eye that a jagged edge is really smooth. Anti-Aliasing is often referred in games and on graphics cards. In games especially the chance to smooth edges of the images goes a long way to creating a realistic 3D image on the screen. Anti-Aliasing does not actually smooth any edges of images it merely fools the eye. Blown up letter a with no anti-aliasing: Had anti-aliasing applied: You can still tell that the letter of the left is jagged but the letter on the right looks a lot smoother and less blurry than the example above. The image has been shrunk down back to normal size. Anti-Aliasing brings a much more pleasing image to the eye. Something like what comes out of a high class printer rather than what you can be used to seeing when on a computer screen.
HA1 - Technical File – Resolution Resolution is the number of pixels in a linear inch—pixels per inch (or PPI), but it is most commonly referred to as dots per inch (DPI). The more pixels, or “dots,” per inch, the higher your image resolution will be. With colour images, each pixel can be one of 16 million different colours. For black and white images, there are 256 gradations of gray pixels ranging from black to white: 0 (black) through 255 (white). More pixels means higher resolution, which creates better image quality because you end up with more realistic representations of colour, better gradations of both individual colours and gray tones, and crisper images in general.
HA1 - Technical File – Aspect Ratio The aspect ratio of a shape is the ratio of its longer dimension to its shorter dimension. It may be applied to two characteristic dimensions of a three-dimensional shape, such as the ratio of the longest and shortest axis, or for symmetrical objects that are described by just two measurements, such as the length and diameter of a rod. The aspect ratio of a torus is the ratio of the major axis R to the minor axis r . For a rectangle, the aspect ratio denotes the ratio of length to width of the rectangle. An aspect ratio of 1:1 is a square . From left to right: From left to right: 1.3 = 4:3: Some (not all) 20th century computer monitors (VGA, XGA, etc.), standard-definition television 1.414… = √2:1: International paper sizes (ISO 216) 1.5 = 3:2: 35 mm film, iPhone displays 1.6 = 16:10, widely used widescreen computer displays (WXGA) 1.618…: Golden ratio, close to 16:10 1.6 = 5:3: super 16 mm, a standard film gauge in many European countries 1.7 = 16:9: widescreen TV
HA1 - Technical File – File Formats A file format is a particular way that information is encoded for storage in a computer file. Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for different kinds of information. Within any format type, e.g., word processor documents, there will typically be several different formats. Sometimes these formats compete with each other. File formats are divided into proprietary and open formats. Some file formats are designed for very particular sorts of data: PNG files, for example, store bitmapped images using lossless data compression. Other file formats, however, are designed for storage of several different types of data: the Ogg format can act as a container for many different types of multimedia, including any combination of audio and/or video, with or without text (such as subtitles), and metadata. A text file can contain any stream of characters, encoded for example as ASCII or Unicode, including possible control characters. Some file formats, such as HTML, Scalable Vector Graphics and the source code of computer software, are also text files with defined syntaxes that allow them to be used for specific purposes
HA1 - Technical File – colour models A colour model is an abstract mathematical model describing the way colours can be represented as tuples of numbers, typically as three or four values or colour components. When this model is associated with a precise description of how the components are to be interpreted (viewing conditions, etc.), the resulting set of colors is called colour space. This section describes ways in which human colour vision can be modelled RGB colour model Media that transmit light (such as television) use additive colour mixing with primary colours of red, green, and blue, each of which stimulates one of the three types of the eye's colour receptors with as little stimulation as possible of the other two. This is called "RGB" colour space. Mixtures of light of these primary colours cover a large part of the human colour space and thus produce a large part of human colour experiences. This is why colour television sets or colour computer monitors need only produce mixtures of red, green and blue light.
HA1 - Technical File – colour models It is possible to achieve a large range of colors seen by humans by combining cyan, magenta, and yellow transparent dyes/inks on a white substrate. These are the subtractive primary colours. Often a fourth black is added to improve reproduction of some dark colors. This is called "CMY" or "CMYK" color space. The cyan ink absorbs red light but transmits green and blue, the magenta ink absorbs green light but transmits red and blue, and the yellow ink absorbs blue light but transmits red and green. The white substrate reflects the transmitted light back to the viewer. Because in practice the CMY inks suitable for printing also reflect a little bit of color, making a deep and neutral black impossible, the K (black ink) component, usually printed last, is needed to compensate for their deficiencies. The dyes used in traditional color photographic prints and slides are much more perfectly transparent, so a K component is normally not needed or used in those media. CMYK color model
HA1 - Technical File – Adobe Photoshop Photoshop is a popular image changing software package. It is widely used by photographers for changing photographs (fix colors, reduce noise, add effects, fix brightness/contrast) and by graphic designers and Web designers to create and change images for web pages. Photoshop works on computer systems like Windows and Mac. The software is made by the company Adobe. There is also a version named Photoshop Elements, made for the home user that does not want to buy the full version that is more expensive. The current version is Photoshop CS5, which was released in April 2010.
HA1 - Technical File – Adobe illustrator Adobe Illustrator is a vector graphics editor developed and marketed by Adobe Systems. Illustrator is similar in scope, intended market, and functionality to its competitors, CorelDraw and Macromedia FreeHand Versions 1–1.6 (Illustrator 88) Versions 2–5 Versions 6–10 Versions CS–CS5
HA1 - Technical File – Adobe InDesign Adobe InDesign is a software application produced by Adobe Systems. It can be used to create works such as posters, flyers, brochures, magazines, newspapers and books. In conjunction with Adobe Digital Publishing Suite InDesign can publish content suitable for tablet devices. Graphic designers and production artists are the principal users, creating and laying out periodical publications, posters, and print media. It also supports export to EPUB and SWF formats to create digital publications, and content suitable for consumption on tablet computer devices. The Adobe InCopy word processor uses the same formatting engine as InDesign. InDesign 1.0 (codenamed K2): August 31, 1999. InDesign 1.5 (codenamed Sherpa): April 2001. InDesign 2.0 (codenamed Annapurna): January 2002 (just days before QuarkXPress 5). First version to support Mac OS X and native transparencies & drop shadows. InDesign CS (codenamed Dragontail) and InDesign CS PageMaker Edition (3.0): October 2003. InDesign CS2 (4.0) (codenamed Firedrake): shipped in May 2005. InDesign Server (codenamed Bishop): released October 2005 InDesign CS3 (5.0) (codenamed Cobalt): April 2007. First Universal binary versions to natively support Intel-based Macs, Regular expression, Table styles, new interface InDesign CS3 Server (codenamed Xenon): released May 2007 InDesign CS4 (6.0) (codenamed Basil): Introduced September 23, shipped in October 2008. InDesign CS4 Server (codenamed Thyme) InDesign CS5 (7.0) released April 2010 InDesign CS5.5 (7.5) released April 2011