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# Ha1 technical file

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### Ha1 technical file

1. 1. HA1 - Technical File – Zoe Armitage
2. 2. 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 &quot;anti-aliasing&quot;. 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:
3. 3. 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.
4. 4. 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.
5. 5. 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.
6. 6. HA1 - Technical File – Aspect Ratio The aspect ratio of an image is the ratio of the width of the image to its height, 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 centimetres wide and 9 centimetres high. A third is 8 yards wide and 4.5 yards high.
7. 7. 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 can be divided into proprietary and open formats. Gif: supports up to 8 bits per pixel thus allowing a single image to reference a palette of up to 256 distinct colours. The colours are chosen from the 24-bit RGB colour space. Jpeg: 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. Tiff: stands for Tagged Image File Format is a file format for storing images, popular in the graphic artists, the publishing industry, and both amateur and professional photographers in general Eps: documents that describe an image or drawing and can be placed within another PostScript document. Psd: file format used to create and edit images in Adobe Photoshop Pdf: file format, created by Adobe Systems, is used for representing documents in a manner independent of application software, hardware, and operating systems
8. 8. 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 colours is called colour space. This section describes ways in which human colour vision can be modelled. RGB: is an additive colour model in which red, green, and blue light is added together in various ways to reproduce a broad array of colours. The name of the model comes from the initials of the three additive primary colours, red, green, and blue. CMYK: is a subtractive colour model, used in colour printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some colour printing: c yan, magenta, yellow, and key (black).