MultimediaMultimedia is everything you can see or hear.
Describe any application or technologythat can be used to represent :-Text, image, sound, animation, videoUsing a combination of moving pictures,sound, music and words especially incomputer or entertainment.
Multimedia ElementsDigital Image Main Points: Introduction. The importance of Image. Image types. Image processing & image matching . Image representation and calculating filesize.
Introduction Using of image and graphics overcenturies ago, and people usedimages instead of texts. ( One image is better than 1000words.). Bartilean system in 1920 was the firstsystem that used image processingmethod to transfer the newspaper fromLondon to New York over Atlantic ocean,which decreased the sending time fromone week to 3 hours.
Image processing is used in Medicine( X-rays , Ultra sound , endoscopy,RMI), in Mining (Patrol , cold , …), inspace (NASA) in Military Purposes,and in many areas(Education,Telecommunications, Simulation).
Importance of image: Since 1964 , the image processing is agrowing area and now ( in 5th Generation)computers are using image and audio tocommunicate with the user. Image processing is used in space system(Ringer – 7) which sent images from the Moon in1964. Also used in military purposes as mentionedearlier. Image processing is an important for anycomputer area and is a rich research
Digital Image representation: Digital Image is composed of number ofpixels(picture element) and it can berepresented using 2D array ( Matrix ).( Nx N array ) For monochrome images ( B / W) ( Mono TV is 512 x 512 ) image can be expressed as afunction(relation )like this :1 0 10 0 11 1 1
f(x,y) = 0 ( black point).f(x,y) = 1 ( white point).( Ibn El-Haithem discovered that eyecan’t see in darkness ).
Image Types:There are three types of image:Binary Image.Gray Image.Color Image.Binary Image : it represented as one pixel inone bit ( e.g 100 pixel stored in 100 bits)Gray Scale image :.whitetoblackfromshadesmonochromaticofrangeaisGrayscaleTherefore, a grayscale image contains only shades of gray and nocolor.white)andblack(orgrayscaleassavedbecanimagesdigitalWhileimages, even color images contain grayscale information. This is.coloritsofregardlessvalue,luminanceahaspixeleachbecause
Luminance can also be described asbrightness or intensity, which can bemeasured on a scale from black (zerointensity) to white (full intensity). Mostsupport a minimumfile formatsimageof 8-bit grayscale, which provides 2^8or 256 levels of luminance per pixel.Some formats support 16-bit grayscale,which provides 2^16 or 65,536 levels ofluminance.
Color Image:thatdigital imageis a(digital) color imageA.pixelinformation for eachcolorincludesFor visually acceptable results, it is necessarysamples(and almost sufficient) to provide three(color channels) for each pixel, which areinterpreted as coordinates in some color space.(Red , Green , Blue) color space isRGBThecommonly used in computer displays.A color image has three values per pixel andthey measure the intensity and chrominance oflight.Thus they used 24 bit to represent each
Image Matching(Recognition)Steps: Digital image processing is the use ofcomputer algorithms to perform imageprocessing on digital images. As a subcategoryor field of digital signal processing, digitalimage processing has many advantages overanalog image processing. It allows a muchwider range of algorithms to be applied to theinput data and can avoid problems such as thebuild-up of noise and signal distortion duringprocessing. There are 6 steps to perform image matchingprocessing(comparing of two images):1. Image Scanning of capturing ( by using
3- Segmentation : means separating ofimportant information (e.g extractingof body from background).4- Feature Extraction: (extracting offeatures (attributes ).5- Feature Classification(grouping offeatures).6- Image understanding(Matching)
Image Representation: Depth: the depth of an image is thenumber of bits used to representeach pixel.e.g in B/W (bitmap image ) : the depthis calculated as :One bit for each pixel.4 bit: represents 16 colors(2 ^ 4 ):used in low resolution screens.
8 bit: can have 256 colors.8 bit gray : can have 256 gray levels.16 bit : can have 65,536 colors (hi colorin windows).16 bit divided into ( 5 bits for Red , 6bits for Green , 5 bit for Blue).24 bit: can have 16,777,216 colors eachbyte is used to represent the intensity ofa primary color(RGB). And each colorcan have 256 different levels.
Resolution : How much details animage can have , there are severalresolutions relating to image.1- Image Resolution : is the number ofpixels in an image ( e.g 320 x 240 =76000 pixels).2- Display ( Monitor ) Resolution: referto number of dots per inch ( dpi) on amonitor (windows usually has 96 dpiresolution)
Example : A 288 x 216 imagedisplayed on a monitor with 96 dpiwill be :[ 3 inch x 2.25 inch]( image size)3- Output Resolution: refer to numberof dot per inch on a hard copy(output device).Many printers have 300 dpi or 600 dpiresolution.( the above image printed on a 300 dpi
Vector Graphics: instead of using pixels , objectscan be represented by their attributes such as ,size , color , location.This type of graphics known as vector graphic.Vector graphic file contains graphics primitives forexample rectangle , circle , lines.There are many languages for describing vectorgraphics ( e.g VRML , SVG).
Calculation file size :File size = depth x image size[Depth (k)=2 ^ k = n , n is number of levels][Image Size = Area x R ^ 2]Calculation of image size steps:1- calculate k [ 2^ k = n , n is numberof levels)2- calculate the total number of pixelsTNP = area x R^2 ( R, Resolution )3- calculate the file sizeFS = [TNP x K ] KB
Example:A 32 level gray image with 10 dpiresolution and 7 x 8 inch , calculatethe file size (required space in Harddisk).Steps:1- cal k = 2 ^ k = n2 ^ k = 32 , k = 5 bits.(k is depth).2- cal TNP = area x R ^ 2= 7 x 8 x 100 = 5600 pixels.3- cal file size
H.W Calculate the File size for thefollowing images:1- A 256 color image with a resolutionof 5 dpi and an area of 100 inch.2- a binary image with 36000 pixels.[Hint: there is a relation between theimage resolution and the filesize][high resolution requires big sizeon the disk]