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HA1 – Raster Images Many Images seen on your computer are raster graphics, pictures found on the internet and photos taken on your digital camera are raster graphics. Raster graphics are made up of grid pixels, referred to as a bitmap. The larger the image the more disk space the image file will take up, for example, a 640 x 480 images requires information to be stored for 307,200 pixels, while a 3072 x 2048 image (from a 6.3 megapixel digital camera) needs to store information for a massive 6,291,456 pixels. Because a raster graphic needs to store so much information, large bitmaps require large file sizes. Fortunately, there are several image compression algorithms that have been developed to help reduce big file sizes. JPEG and Gif are two of the most common compressed image formats on the internet. But many other types of image compression are available. Raster graphics can be scaled down with no loss of quality, but enlarging a bitmap image causes it to look blocky and ‘pixelated’. For this reason, vector graphics are often used for certain images, such as logo companies logos, which need to be different scales.
HA1 - Technical File – Vector Images Unlike JEPGS, GIFS, and BMP images, vector images are not made up of grid pixels, they are made up of paths, which are defined by a start and end point, along with curves, points and angles along the way. A path can be a line, a square, a triangle or a curvy shape. The paths can be used to create simple shapes and drawings or even complex designs. Paths are also used to define the characters of specific typefaces. As a vector graphic is not made up of specific number of dots, they can be scaled to a larger size and not lose any image quality. If a raster image is blown up, it will appear blocky or ‘pixelated.’ But when a vector graphic is blown up, the edges of each object within the graphic stay smooth and clean. This makes vector graphics ideal for company logos, which need to be small enough to fit on business cards but big enough to fit on billboards. Common types of vector graphics include Adobe Illustrator, Macromedia Freehand, and EPS files. Many flash animations also used vector images, since they scale better and take up less space than bitmap images.
HA1 – 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. Remember though that Anti-Aliasing does not actually smooth any edges of images it merely fools the eye. Like a lot of things they are only designed to be good enough. If you can't tell the difference then that's fine. Lets take a look at the example below to demonstrate the effects of Anti-Aliasing. The letter on the left is a blown up letter a with no anti-aliasing. The letter on the right has had anti-aliasing applied to it. In this blown up form it looks like its simply blurred but if we reduce the size down to a more standard size you may see the difference. Now look closely at the two letters. 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. Remember I have only shrunk the image down back to normal size and have not altered anything else to the image at all. So as you can see, 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 – Resolution Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail. Image resolution can be measured in various ways. Basically, resolution quantifies how close lines can be to each other and still be visibly resolved. Resolution units can be tied to physical sizes (e.g. lines per mm, lines per inch), to the overall size of a picture (lines per picture height, also known simply as lines, TV lines, or TVL), or to angular subtenant. Line pairs are often used instead of lines; a line pair comprises a dark line and an adjacent light line. A line is either a dark line or a light line. A resolution of 10 lines per millimeter means 5 dark lines alternating with 5 light lines, or 5 line pairs per millimeter (5 LP/mm). Photographic lens and film resolution are most often quoted in line pairs per millimeter. Above is an illustration of how the same image might appear at different pixel resolutions, if the pixels were poorly rendered as sharp squares (normally, a smooth image reconstruction from pixels would be preferred, but for illustration of pixels, the sharp squares make the point better).
HA1 – Aspect ratio The aspect ratio is an image projection attribute that describes the proportional relationship between the width of an image and its height. It is expressed as two numbers separated by a colon. That is, for an x : y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this same length unit, the height will be measured to be y units. For example, consider a group of images, all with an aspect ratio of 16:9. One image is 16 inches wide and 9 inches high. Another image is 16 centimeters wide and 9 centimeters high. A third is 8 yards wide and 4.5 yards high.
HA1 – 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. The Graphics Interchange Format (GIF ; or ) is a bitmap image format that was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability. The format supports up to 8 bits per pixel thus allowing a single image to reference a palette of up to 256 distinct colors. The colors are chosen from the 24-bit RGB color space. It also supports animations and allows a separate palette of 256 colors for each frame. The color limitation makes the GIF format unsuitable for reproducing color photographs and other images with continuous color, but it is well-suited for simpler images such as graphics or logos with solid areas of color. In computing, JPEG ( [pronounced as jay - peg] is a commonly used method of lossy compression for digital photography (image). The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality. JPEG compression is used in a number of image file formats. JPEG/Exif is the most common image format used by digital cameras and other photographic image capture devices; along with JPEG/JFIF, it is the most common format for storing and transmitting photographic images on the World Wide Web.  These format variations are often not distinguished, and are simply called JPEG. TIFF (originally standing for Tagged Image File Format ) is a file format for storing images, popular among graphic artists, the publishing industry, and both amateur and professional photographers in general. As of 2009, it is under the control of Adobe Systems. Originally created by the company Aldus for use with what was then called "desktop publishing", the TIFF format is widely supported by image-manipulation applications, by publishing and page layout applications, by scanning, faxing, word processing, optical character recognition and other applications. Adobe Systems, which acquired Aldus, now holds the copyright to the TIFF specification. TIFF has not had a major update since 1992, though several Aldus/Adobe technical notes have been published with minor extensions to the format, and several specifications, including TIFF/EP (ISO 12234-2), TIFF/IT (ISO 12639), TIFF-F (RFC 2306) and TIFF-FX (RFC 3949)  have been based on the TIFF 6.0 specification. Encapsulated PostScript , or EPS , is a DSC-conforming PostScript document with additional restrictions which is intended to be usable as a graphics file format. In other words, EPS files are more or less self-contained, reasonably predictable PostScript documents that describe an image or drawing and can be placed within another PostScript document. At minimum, an EPS file contains a BoundingBox DSC comment, describing the rectangle containing the image described by the EPS file. Applications can use this information to lay out the page, even if they are unable to directly render the PostScript inside. EPS, together with DSC's Open Structuring Conventions, form the basis of early versions of the Adobe Illustrator Artwork file format. The .PSD (Photoshop Document), Photoshop's native format, stores an image with support for most imaging options available in Photoshop. These include layers with masks, color spaces, ICC profiles, transparency, text, alpha channels and spot colors, clipping paths, and duotone settings. This is in contrast to many other file formats (e.g. .EPS or .GIF) that restrict content to provide streamlined, predictable functionality. PSD format is limited to a maximum height and width of 30,000 pixels. Portable Document Format ( PDF ) is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it.
Adobe Photoshop is a graphics editing program developed and published by Adobe Systems Incorporated . 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, Xara Designer Pro and Macromedia FreeHand. The latest version, Illustrator CS5, is the fifteenth generation in the product line. 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. InDesign can also publish content suitable for tablet devices in conjunction with Adobe Digital Publishing Suite. HA1 – Adobe Photoshop, Illustrator and Indesign.
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 color 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 color vision can be modeled. The RGB color model is an additive color model in which red, green, and blue light is added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue. The CMYK color model ( process color , four color ) is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: c yan, m agenta, y ellow, and k ey (black). Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the abbreviation. HA1 – Colour Models