Aims of the report
The aim of this report is to research into basic hardware and software principle’s used in audio and visual processing. Information about RGB colour model and how it used on computer displays will be provided, Nyquist theorem, WAV structure which includes header information, logic gates with information about the 7 gates which are used, basic circuits used audio visual systems and how binary is used for audio quality. Research and experimentation will be done into the topics to gain a better understanding. Representation of images and Bitmap image.
On most computer displays the screen imaged is made up of discrete units known as pixels. The pixels are arranged in ordered for the image to form a 2 dimensional array. Over the years pixels that are displayed on PC monitors have increased immensely. Before 640 x 480 display produces (307,200 pixels). Now monitor resolutions of 1920 x 1080 producing (2,073,600 pixels), 4K 3840 x 2160 producing (8,294,400 pixels) and with more pixels per inch sharper image quality. A bitmap image is a format which is uses bits of 1 and 0 to store data. A bitmap is a digital image created of a lot of dots. When viewed each dot corresponds to an individual pixel on a display and can be assigned a different colour and these dots will represent a rectangular image. The Bitmap format includes a header which gives information about the file size, number of colours used in image and also a list of pixels with the matching colours. A disadvantage of a bitmap image is they are memory intensive, so the higher the resolution the larger the file will be. Most images nowadays on the web are compressed to JPG, GIF and PNG so they download and open on web pages quicker. Another disadvantage of bitmap images are when resizing the image the pixels will become pixelated producing bad quality images which will become blurry. RGB model and what’s it used for?
RGB model is a common colours used for digital image representation and there are three main primary colours which are red, green and blue which are mixed to produce more colours and displayed on a monitor. The main reason these three colours are the primary colour is because the human’s eye is naturally more sensitive to red, green and blue. “The RGB colour space is based upon the portion of the electromagnetic spectrum visible to humans (i.e. the continuous range of wavelengths in the approximate range 400-700nm). The human eye has three different types of colour receptor over which it has limited (and nonuniform) absorbency for each red, green and blue wavelengths”. (Solomon & Breckon, 2010, p.1.41). Some of the input devices which use RGB include colour TV’s, Videos cameras, mobile phones, LED displays and video projectors. Colour printers use a different colour model called CMYK. How RGB is used for images on Computers?
Computer systems can be used to represent everything through numbers by using binary numbers which consists of numbers zero and one. In computers the numbers are represented by electronic switches. An open switch represents a zero and a closed switch represents a one. These are known a bits which are stored in the computer’s memory. Eight bits make a byte of data and most colours are represented in computers using 8 bit numbers which basically means that that a set of eight zeroes and ones is used to represent a given colour. By using the eight zeroes and ones there is 256 combinations to represent different colours. For example the decimal integer 0 can be shown in 8-bit binary digits which is in 3 bytes as 00000000, 00000000, and 00000000 while the decimal integer 255 is represented as 11111111, 11111111 and 11111111. Some computer programs represent colours in hexadecimal numbers. Hexadecimal has 16 numerals represented by our normal decimal numbers and the first 6 letters of the alphabet (0123456789ABCDEF). For example red, green and blue in hexadecimal is (FF,00,00), (00,FF,00) and (00,00,FF). A bitmap image...
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