Images

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Images

Post  admin on Tue 29 Jun 2010, 7:34 am



The information contained within a pixel.

Images are pictures, such as drawings, paintings or photographs. Images are either bit-mapped graphics or vector graphics.

A Pixel, or picture element, is the smallest part of the screen that can be controlled by the computer. The total number of pixels within a set space, for example, pixels per inch (ppi) called its resolution. Bit-mapped graphics store information (such as colour -RGB, CMYK, tone-HSL, shade etc) about each individual pixel on the picture, they produce high quality images where shading and detail are needed but when transformed they become ragged and suffer loss of resolution. Enlarging bitmapped images creates a staircase pattern called aliasing. Bit-mapped images require large amounts of storage, which is why they are stored in compressed formats such as GIF and JPEG.

Vector graphics are made up of objects, such as a straight line, a curve, or a shape. Each object is defined by its characteristics, such as position, line width and pattern. This is why it is usually smaller in file size, however processing required to transform the data into a displayed image is greater. Any property can be independantly altered without affecting the rest of the image, unlike bitmap which changes pixels. These characteristics are stored as mathematical expressions. Enlargements on vector graphics do not cause any loss in quality unlike bit-mapped graphics, making them suitable for design drawings but unsuitable for photographs. Some common formats for vector graphics include CGM, EPS and WMF.




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