Graphics ITGS Pixel Short for “Picture Element” A single dot on a monitor or printed document. The smallest rectangular area of an image that can be manipulated on a monitor or printer, or stored in memory. A pixel has a unique associated colour Pixel colours/shades A pixel shows only one colour at a given instant, but the possible colours may vary according to the number of bits we assign to each pixel. If we assign a single bit (1 or 0) to a pixel we can give that pixel only two colours. If we assign two bits to a pixel we can give that pixel four colours (00,01,10,11). More colours / shades Bits per pixel Number of different colours 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256 n 2n Pictures & Formats A picture is a set of pixels of different colours placed in a particular pattern. Pictures must be saved to disks as a sequence of bits. There are several ways of translating a picture to a series of bits. This will give name to the format of the image file. Some of them highly compress the image (JPEG, GIF) occupying less space and some of them not so much (BMP). Examples: JPEG, GIF, BMP, TIFF, WPG, PIC,PIX. Another graphic format distinction Graphic file formats can be: Pixeled or Bitmapped Object-oriented (or vector based) Object-Oriented vs. Bitmapped Object oriented Bitmapped Are stored as a series Are stored as pixels at of lines or vectors. given coordinates. Have smooth edges Have sharp edges Can be enlarged Cannot be enlarged without any loss of without loss of image image quality. quality. Not very good for Photographs and photographs or complex complex images can pictures (they occupy perfectly be stored (and too much) compressed to a reasonable extent) Another comparison chart can be found in www.british.edu.uy/it_dept/itgs/graphics.jpg Quality vs. Storage space quality Storage space Drawing vs. Painting software Drawing software manages objects Painting software manages bitmaps Graphics issues Monitor vs. Printer quality Image digitalisation methods Easy to replicate works of art Easy the violation of intellectual property (OCR) Computer Aided Design (CAD) It is the use of computers to design products. Used mainly by engineers, designers and architects. It can help to visualize the product better It can prevent design error, therefore preventing serious catastrophes. It can take very much less time to design a product. It can lower the costs as the designer can avoid buying experimental material. CAD...some disadvantages Unskilled designers can build design- poor products that may cause future accidents. It may require lots of storage capacity. The design may turn too complex and have design problems It is limited to the drawing skills of the CAD software. Computer Aided Manufacture (CAM) CAM systems are sometimes integrated with a computer-aided design system (CAD). Very useful for circuit designers.
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