Chapter 7

Transcript

1 Digital Media 2 Bitmap Graphics Bitmap graphic – “raster graphic graphic”, ”, consists of a grid of dots, and the color of each dot is stored as a binary number 3 Bitmap Graphics Often used to create realistic images Cartoons in video games 3- D graphics software Digital cameras E- mail photos 4 Bitmap Graphics Paint software – graphics software for creating bitmap graphics Adobe Photoshop Jasc Paint Shop Pro Microsoft Paint 5 Bitmap Graphics Scanner – converts printed pages and images into a bitmap graphic Divides image into fine grid of cells cells,, and assigns a digital value for the color of each cell Values are transferred to your computer’s disk and stored as a bitmap 6 Bitmap Graphics 7 Bitmap Graphics Digital camera – digitizes real objects Takes photo in digital format, which you can then transfer directly to your computer 8 Bitmap Graphics The type of memory module used by a digital camera depends on the brand and model Flash memory – popular technology for digital camera memory modules Holds data without consuming power 9 Bitmap Graphics 10 Bitmap Graphics Direct cable transfer – Fire Wire ports are used to transfer data Infrared port – cameras “ beam beam”” the data to computer’s infrared port Memory card readers – small device connected to computer and designed to read flash cards Floppy disk adapters – adapter shaped like a floppy with slot for a flash memory module 11 Bitmap Graphics 12 Bitmap Graphics You can use graphics software to modify or edit bitmap graphics by changing individual pixels Retouch Repair Remove red eye or erase “ rabbit ears ears”” Bitmap graphics require large amounts of storage storage,, and take long time to load 13 Bitmap Graphics Resolution – dimensions of the grid that forms a bitmap graphic Number of horizontal and vertical pixels that it contains 150 x 100 – 150 pixels across and 100 pixels high 14 Bitmap Graphics High-- resolution graphics contain more data than low High low-- resolution Better printouts Megapixels – total number of pixels in a graphic 15 Bitmap Graphics Each pixel is stored as one or more bits More pixels means larger file size 16 Bitmap Graphics Bitmap has no fixed physical size Size depends on density Graphic retains same resolution no matter how much you stretch or shrink the graphics physical size 17 Bitmap Graphics 18 Bitmap Graphics Most graphics software lets you specify the size at which image is printed without changing the resolution of the bitmap graphic Get better printout if an image meets or exceeds the printers dpi (dots per inch inch)) 19 Bitmap Graphics Typically , one pixel corresponds to one pixel on the screen Typically, If image is larger than screen screen,, you will have to scroll 20 Bitmap Graphics Cropping – process of selecting part of an image Resolution dependent – quality of the image depends on its resolution Can reduce image quality If you attempt to enlarge a bitmap, computer must add pixels Pixel interpolation – creates new pixels by averages the colors of nearby pixels Pixelated – undesirable bitmappy appearance 21 Bitmap Graphics 22 Bitmap Graphics Color depth – is the number of colors that are available for use in an image Larger number number,, better quality and larger file size 23 Bitmap Graphics Monochrome bitmap – pixel could b e “on” or “off” On – represented by a 1 bit Off – represented by a 0 bit Each row of the bitmap stored as 0s and 1s Size of file given by resolution in case of monochrome bitmaps Requires very little storage 24 Bitmap Graphics 25 Bitmap Graphics True color bitmap (24 24-- bit bitmap bitmap)) – 16.7 million colors Each pixel requires 3 bytes of storage Color based on intensity levels or red red,, green, blue 8 -bits red red,, 88 -bits green, 8 -bits blue (24 (24--bits) 32-- bit bitmap – 16.7 million colors plus special effects 32 26 Bitmap Graphics Reducing color depth can reduce size of file To reduce color depth depth,, manipulate color palette Color palette – digital version of artist’s palette that holds the selection of colors for use 256 colors – eight bits per pixel (1/3 size required for true color bitmap) 27 Bitmap Graphics 28 Bitmap Graphics Use color palette or color picker tool Grayscale palette – displays an image using shades of gray (usually (usually 256 shades of gray) System palette – selection of colors used by the operating system Windows has 20 permanent colors and 236 that can be changed Web palette – standard set of colors used by the Internet Web browsers 29 Bitmap Graphics n Dithering – uses patterns composed of two or more colors to produce the illusion of additional colors and shading shading,, relying on the human eye to blend colors and shapes 30 Bitmap Graphics Bitmap graphics that you wish to print should remain in True Color format Those sent in e- mail or posted on Web site should be reduced to 256-- color palette 256 31 Bitmap Graphics BMP – native bitmap graphic file format of Microsoft Windows OS PCX – one of original personal computer bitmap graphics file formats (8 -bit – 256 color color)) TIFF (Tag Image File Format) – highly flexible and platform platform--independent graphics file format Supports True Color Used by scanners and digital cameras 32 Bitmap Graphics JPEG – graphics format with built built-- in compression You control level of compression Uses True Color GIF – limited to 256 colors PNG – 48 48-- bit True Color Color,, compresses without losing data Public domain format 33 Bitmap Graphics Selecting the best graphics file format to use depends on what you intend to do with the image Scanned and digital images – could be stored as JPEG or TIFF format Images for web pages – GIF or JPEG format Designing Windows controls – BMP format 34 Digital Media 35 Vector and 3-D Graphics Vector graphic – consists of set of instructions for rere- creating a picture Instead of storing the color value for each pixel, a vector graphic file contains the instructions that the computer needs to create the shape shape,, size size,, position, and color for each object in an image 36 Vector and 3-D Graphics 37 Vector and 3-D Graphics Flat, cartoon cartoon-- like quality Filename extension .wmf .dxt . mgx .eps .pict .cgm 38 Vector and 3-D Graphics 39 Vector and 3-D Graphics Vectors resize better than bitmaps Vector images usually require less storage space than bitmaps It is easier to edit an object in a vector graphic than an object in bitmap graphic Vector graphics tend not to produce images that are as realistic as bitmap images 40 Vector and 3-D Graphics 41 Vector and 3-D Graphics Digitizing tablet – device that provides a flat surface for a paper paper--based drawing 42 Vector and 3-D Graphics Drawing software – vector graphics software Helps you easily edit individual objects by changing their sizes sizes,, shapes,, positions or colors shapes 43 Vector and 3-D Graphics 44 Vector and 3-D Graphics Gradient – smooth blending of shades from one color to another another,, or from light to dark Metafiles – graphics that contain both bitmap and vector data Apply bitmap texture to vector graphic 45 Vector and 3-D Graphics 46 Vector and 3-D Graphics n n 47 Rasterization – works by superimposing a grid over a vector image, and determining the color for each pixel Once converted converted,, the resulting graphic no longer has the qualities of a vector graphic Vector and 3-D Graphics Tracing software – locates the edges of objects in a bitmap image and converts the resulting shapes into vector graphics objects 48 Vector and 3-D Graphics Browsers support a limited number of graphics formats – Gif and Jpeg Support for vector graphics has been slow, but plug plug-- ins and players are currently available 49 Vector and 3-D Graphics n SVG (Scalable Vector Graphics Graphics)) – designed for the Web • Automatically resized when displayed on different screens • Uses tag n 50 Flash graphics – can b e static or animated and require less space than SVG graphics graphics,, but require a browser plug plug-- in to be viewed Vector and 3-D Graphics Vector graphics appear with same consistent quality on all computer screens Any text contained in a vector image is stored as actual text text,, not just a series of colored dots Vector graphics on the Web have compact file sizes 51 Vector and 3-D Graphics 3- D graphics – stored as a set of instructions Wireframe – framework for a 33- D graphic Rendering – process of covering a wireframe with surface color and texture Ray tracing – technique for adding light and shadows to a 33- D image 52 Vector and 3-D Graphics 53 Vector and 3-D Graphics 54 Vector and 3-D Graphics 3- D graphics software AutoCad,, Caligari truSpace AutoCad High-- end workstations High 500 MHz Pentium or Macintosh G3 or better High--resolution monitor High Graphics card with lots of memory 55 Vector and 3-D Graphics 56 Vector and 3-D Graphics 3 -D graphics can be animated to produce special effects for movies movies,, or create interactive, animated characters and environments for 33 -D computer games Pixar Animation Studios DreamWorks Special effects can be created and incorporated into final footage 3 -D computer game animation happens in “real “ real--time ” 57 Vector and 3-D Graphics Can be created on a standard PC or iMac using commercially available software Commonly expensive and have a steep learning curve Shareware programs are available 3-D Graphics InfoWeb 58 Digital Media 59 Desktop Video Desktop video – videos that are constructed and played using a personal computer Stored on hard disks disks,, CDs CDs,, DVDs DVDs,, videotapes , or the Web Not quite like standard of DVD movies movies,, but suitable for variety of personal and professional uses 60 Desktop Video Video is composed of a series of frames Each frame is essentially a still picture ( can b e stored as bitmap graphic)) graphic Frame rate – number of frames per second Feature films – 24 fps ( frames per second) Desktop video – 15 fps 61 Desktop Video Most computers equipped for viewing videos videos;; however however,, video playback quality can vary Depends on Microprocessor RAM capacity Capabilities of graphic card For web web,, Internet connection speed is also issue 62 Desktop Video For Internet also need Player – Quicktime , Windows MediaPlayer 63 Desktop Video Several file formats are popular for desktop videos AVI QuickTime MPEG RealMedia ASF 64 Desktop Video The basic process consists of following steps Shoot the video footage Transfer the footage to your computer’s hard disk Edit the video and soundtrack Output the video in its final format by selecting frame rate, window size size,, file format, and compression levels 65 Desktop Video You can use analog or digital video camera to shoot footage Digital video camera – stores footage as a series of bits Analog video camera – normal video camera Video signal stored as continuous track of magnetic patterns Must be digitized Videoconferencing cameras – attach to computer 66 Desktop Video 67 Desktop Video Captures video data in digital format which can then be directly transferred to a computer for editing Produce higher quality video than analog or videoconferencing cameras Images tend to be sharper and more colorful Higher quality of original video video,, the better the final video will look 68 Desktop Video 69 Desktop Video When processed and stored stored,, some of image data is eliminated to reduce the video file to a manageable size To produce good quality video Use a tripod to maintain a steady image Move the camera slowly Zoom in and out slowly Direct your subjects to move slowly Position your shot well Ask the subjects of your video to wear solid colored clothing 70 Desktop Video In order to digitally edit edit,, process process,, and store a desktop video video,, you must transfer the video footage from your camera to your computer 71 Desktop Video Basic method for transferring video footage is to send the data over a cable that connects your camera to your computer Equipment depends on your camera and your computer Video capture device – converts analog camera signal into digital data 72 Desktop Video 73 Desktop Video 74 Desktop Video Video capture software – allows you to start and stop the transfer,, and select the display size transfer size,, frame rate, filename filename,, and file format for your video footage 75 Desktop Video Linear editing – recording segments from one videotape onto another tape Non-- linear editing – requires a computer hard disk and video editing Non software Can use random access devices to easily edit and arrange footage Video editing software – lets you edit video into final desktop video 76 Desktop Video 77 Desktop Video After editing editing,, video editing software combines data from all of the video and audio files that you selected into a single file as a desktop video Select file format, QuickTime or AVI A full full--screen True Color image at 1,024x768 resolution requires 2,359,296 bytes; with 24 fps fps,, requires 56,623,104 bytes 10 minutes requires almost 34 GB of storage space To shrink shrink,, decrease size of window window,, number of frames frames,, and select a compression technique 78 Desktop Video 79 Desktop Video To reduce size Decrease the size of the video window Reduce the frame rate Compress the video data Codec (compressor compressor//decompressor decompressor)) – software that compresses a file when a desktop video is created and decompresses the file when video is played MPEG, Indeo Indeo,, Cinepak , DivX , Video 1 80 Desktop Video The ultimate goal is to store a high high-- quality video image in a small file Difficult to predict the result of compression Codec used to compress must be used to decompress the video when it is played Missing codecs account for high proportion of desktop video glitches 81 Desktop Video 82 Desktop Video Streaming video – sends small segment of the video to your computer and begins to play it Web server sends next part of the file to your computer, and so on, until the video ends 83 Desktop Video 2 styles External video – displays a link to a video file 1.5 MB AVI Video Internal video ( inline video video) ) – uses EMBED tag, “ in in--place video video”” 84 Desktop Video 85 Desktop Video Dial -up connections are slow DialTypical 56 Kbps connection reach speeds of only 44 Kbps Video to play At 15 fps fps,, with 256 colors colors,, 357 bytes per frame frame;; playing in a window of 15 by 11 pixels (1/6 of an inch wide wide)) High--speed Internet connections provide much more bandwidth for streaming video High Most Web sites provide one video file that’s optimized for dial dial--up and one optimized for high--speed (DSL, cable high cable,, and ISDN connections) 86 Digital Media 87 Digital Sound Waveform audio is a digital representation of sound sound.. Music,, voice Music voice,, and sound effects can all be recorded as waveforms 88 Digital Sound Sampling rate – refers to number of times per second that a sound is measured during the recording process Expressed in hertz (Hz) Audio CDs have sampling rate of 44.1 KHz Stereo effects effects,, requires 32 bits of storage space for each sample Floppy,, stores only eight seconds of music Floppy 45 minutes of music – 475 MB To conserve space , reduce sampling rate 89 Digital Sound 90 Digital Sound Sound card – contains a variety of input and output jacks, plus audio-- processing circuitry audio Plugs into a PCI expansion slot inside the system unit 91 Digital Sound Digital signal processor – performs three important tasks Transforms digital bits into analog waves Transforms analog waves into digital bits Handles compression and decompression decompression,, if necessary 92 Digital Sound Recognize a waveform audio file by its extension Wave (. (.wav wav)) – created by Windows Audio Interchange Format (. (.aif aif)) – created by Apple RealAudio (.ra) – proprietary format created by RealNetworks MP3 (.mp3) – MPEG format, popularized by Napster 93 Digital Sound 94 Digital Sound Audio software comes in many flavors To play play,, you must use an audio player Microsoft Media Player To record, you may need another software component Microsoft Sound Recorder software Software may be part of your operating system or purchased separately 95 Digital Sound Yes,, files can b e embedded using HTML Yes ”> Streaming format to avoid lengthy delays 96 Digital Sound MP3 is a compressed waveform audio format that stores digitized music music,, vocals,, and narration in such a way that the sound quality is good vocals good,, but file size remains relatively small CD ripper – grabs tracks from audio CD MP3 encoder – converts Wave file into MP3 format MP3 files can be stored anywhere or relocated to a portable MP3 player 97 Digital Sound 98 Digital Sound Synthesized sound – artificially created sound MIDI or synthesized speech MIDI (Musical Instrument Digital Interface) – specifies standard way to store music data MIDI sequence – encoded music stored as .mid . mid , .cmf . cmf,, or .rol .rol Most sound cards are equipped to capture data from a MIDI instrument Wavetable – set of pre pre--recorded musical instrument sounds 99 Digital Sound 100 Digital Sound MIDI is a good choice for adding background music to multimedia projects and Web pages Embed tags are placed within an HTML document MIDI software can b e used to compose your own tunes or get permission to use MIDI file that you find on the Web 101 Digital Sound 102 Digital Sound Speech synthesis – process by which machines produce sound that resembles spoken words Speech recognition (or “voice “voice recognition”) – ability of machine to “understand “understand”” spoken words 103 Digital Sound Phonemes – basic sound units strung together by speech synthesizers Text-- to Text to-- speech software – generates sounds that are played through your computer’s standard sound card Speech synthesis is a key technology in wireless communication 104 Digital Sound Speech recognition software – analyzes the sounds of your voice and converts them to phonemes Next,, the software analyzes the content of your speech; it compares the Next phonemes to the words in a digital dictionary Speech recognition software can be integrated with word processing software so that you can enter text by speaking into a microphone