Multimedia Option Flashcards
Contrast vector and bitmapped graphics
“Vector graphics are created using mathematical formula and are scalable. Bitmapps are created using pixels”
Explain how vector images are stored
“Vector images are stored using mathematical equations (co-ordinates). This means that when they are resized”
Explain how bitmapped images are stored.
Bitmapped graphics are stored by storing individual pixels (dots) which make up an image._Ä©
Give examples of where bitmapped images would be best used?
Photographs!_Ä©
Explain how resolution affects an image.
“Resolution is essentially an images QUALITY. Resolution is the number of pixels in an image”
Define Bit depth
Bit depth is the number of bits required to represent each pixel. We know that: 2^bit depth = number of colours. Also known as colour depth._Ä©
Define colour depth
Colour depth is the number of bits required to represent each pixel. We know that: 2^bit depth = number of colours. Also known as bit depth._Ä©
How do you calculate the file size of an image?
Resolution * Bit depth /8 * 1024
Describe features of TIFF Files
widely supported bitmap format, good with photographic as well as line art graphics (kind of the best of both worlds between jpeg and gif. Can be compressed a little, but not too much. generally about 10 x the file size of the equivalent sized jpeg.
Describe features of BMP Fiels
Uncompressed, good quality files. Generally just used in windows systems.
Describe features of PCX/PICT Files
An older format, that used to be the standard for graphic design. this has been surpassed by other, more standardised file formats.
Describe features of JPEG files
Lossy compression, averages out values of colours near each other to create common areas of colours. Good for photos. Standardised. Does not support transparency, or animation.
Describe features of GIF files
Good for fine line drawings, cartoons, maps, etc. Bitmapped format, but good compression, as uses lossless compression, where quality is restored on extraction. Gif is an 8 bit file format (256 colours) which supports transparency and animation.
Describe features of PNG Files
Good for fine line drawings, cartoons, maps, etc. Bitmapped format, but good compression, as uses lossless compression, where quality is restored on extraction.
Define anti-aliasing
Anti-ailiasing gives the illusion of a higher quality as it may smoothen edges of an image. However anti aliasing takes more to process (graphics card has to do more work) and may worsen the quality (as it is blurrier) on projects that are intended for printed.
Describe features of WMA
WMA files are Windows Media Audio files as these files are optimised for the windows operating system, which may be a negative when a user wants to use it on an apple system (as they need a different codec/program). These files have a low compression and therefore have a higher quality and file size when compared to files such as .mp4.
Describe features of midi files
MIDI (Musical Instrument Digital Interface) files are audio. These files store the sound with formulae, and therefore they may be more easily edited and manipulated by users.
How is a sound file stored in memory
This involves taking a number of samples or Ä_Ù´ÄãslicesÄ_Ù´Ä_ of the sound wave. This is called the sampling rate (Samples per second). Each sample is assigned a number of bits. This is called the sample size (or bit rate). Better quality sound is achieved by increasing the sampling rate and/or the sampling size. These co-ordinates then define the curve that the shape follows. The more of either of these elements, then the greater quality of the curve, therefore the better quality sound.
Define Sampling
Sampling is the process of digitising sound by taking samples of the sound wave in order to correctly map the co-ordinates of the curve that defines the wave.
Describe features of AIFF Files
AIFF is an apple based format that is used to store sound files. AIFF itself is uncompressed, but has variants that are compressed using certain codecs. It is high quality, and a higher file size than say, MP3.
What is the difference betweenMIDI file and a sound file?
A midi file is a programmed sequence of sound that is generated from the sound card, which plays sounds in a particular sequence. Sound files, however are simply recordings of sound, and are typefied by wave files.
What considerations are thereregarding file size of a video?
Frames per second, resolution, length, bit depth
Define:Ä_Ù´û˜ LossyÄ_Ù´û˜ Lossless
Lossy is compression where data is thrown out and it is not restored on decompression. Lossless data is restored on decompression, so that there is very little loss in quality.
Describe features of MPEGFiles (video)
Good compression ratio, highly standardised.
Describe features of AVI Files
Uncompressed, good quality.
What is the difference betweena transition and an effect invideo files?
Transitions occur between two clips (eg, fade in and out) and effects occur on top of the film (eg, colour correction)
What is cel animation?
Traditional hand made animation. Frame by frame, each drawing is done on a frame (traditionally, celluloid) and pieced together to create the illustion of movement
What is path based animation?
Path based animation is where animation follows a particular sequence. (eg, a plane flying across the screen)
What is morphing? Giveexamples.
Morphing involves converting one image to another. Remember Michael Jackson’s Black or White.
What effect does Frame Ratehave on an animation?
It effects the speed and smoothness of movement. Higher frame rates mean a smoother animation. It also effects the file size aas there are more frames per second.
What is modelling in 3DAnimation?
Creating the figure. Imagine modelling in clay. Essentially the same process
Distinguish between warping and morphing
Warping is taking one image and altering it, pushing and pulling it around. Eg, you could make your ears look really big. Morphing is between two images.
How does motion capture work
Motion capture works by placing coloured dots all over an object and videoing this, and mapping this against an animation. This was done with the movie Lord of the Rings (the best movie in the world) for the character of Gollum.
Give advantages of progressively loading images
These can be put on a website so that the website appears to load quicker (kind of like on facebook photos) where the images load quickly in low res by alternating downloaded lines of pixels, and then clarify over time.
What are thumbnails
Preview images shown on a website (think google images)
What is streaming
The transfer of video so that it can be watched while the transfer occurs (as opposed to downloading where you have to wait for the whole thing.
Compare/Contrast two forms of video transfer
Video transfer types are RTSP and HTTP: RTSP allows live streaming and is good on mobile devices. HTTP is traditional streaming. An advantage of HTTP is that you don’t have to restream after you have viewed components. With RTSP, it progressively downloads, then throws away any data that it has streamed in order to save space on your device. This means you have to restream in order to rewatch.
How does buffering work
Buffering is where in a video download process, a small part of the video is downloaded ahead of where you have watched, and saved in the RAM so that you can watch the video more quickly
How is an image file stored?
Each individual pixel is mapped in memory, in terms of it’s location and colour. The number of pixels * amount of bits used per pixel (bit depth) is the file size
What is sampling
A process where sections are taken of a sound file in order to digitise it.
