Multimedia and Graphics Software: Formats, Tools and PYQs

The correct answer is A, Joint Photographic Experts Group. JPEG is named after the committee of the International Organization for Standardization and the International Telecommunication Union that drew up the standard for compressing continuous tone photographs. Its compression is lossy, which means some detail is thrown away for a much smaller file, and it keeps no transparency, so a JPEG logo always carries a background. Option B is wrong because the format has nothing to do with the Java language and predates it in design work. Option C invents an expansion around the word pixel, which is tempting but is not the committee's name. Option D is also invented, and candidates should note that the format is about compression rather than editing. Remember the pair: JPEG for photographs with lossy compression, PNG for lossless images with transparency.

The correct answer is C, GIF. The Graphics Interchange Format, introduced by CompuServe, can store several frames in one file together with the delay between them, which is why short looping animations on the web were long made as GIFs. It uses lossless LZW compression, allows one transparent colour and is limited to a palette of 256 colours, so photographs look banded in it. Option A, BMP, is Microsoft's plain uncompressed bitmap and holds a single still image. Option B, TIFF, can hold multiple pages for scanning and printing but is not used to play animation. Option D, JPEG, is a lossy single frame photographic format with no animation and no transparency. For the exam, link GIF with 256 colours and animation, and PNG with transparency without animation.

The correct answer is B, MPEG-1 Audio Layer III. MPEG stands for Moving Picture Experts Group, and the group defined three audio layers of rising complexity within its MPEG-1 standard; the third layer gave the file extension .mp3. Its compression is lossy and relies on psychoacoustics, discarding sounds a listener is unlikely to hear, which shrinks a recording to roughly a tenth of its uncompressed size. Option A is invented and no standard uses the phrase multi phase audio. Option C sounds plausible because MIDI really is a music protocol, but MIDI and MP3 are different things: MIDI stores instructions, MP3 stores compressed sound. Option D confuses the format with Microsoft's media player software, which plays many formats but gives its name to none of them. Candidates should also keep the companion full forms ready, since MPEG-2 underlies DVD video and MPEG-4 Part 14 gives the familiar MP4 container.

The correct answer is B, PSD. PSD, the Photoshop Document, keeps every layer, mask, channel and adjustment separately so that the artist can go back and change any of them, which an exported JPEG or PNG cannot do because those flatten the picture into one grid of pixels. Option A, CDR, is the native format of CorelDRAW, a vector drawing package. Option C, AI, is the native format of Adobe Illustrator, which is also a vector program and a common distractor because it too comes from Adobe. Option D, SVG, is the open Scalable Vector Graphics format of the World Wide Web Consortium, written in XML. The simple rule to carry into the hall is that Photoshop is raster and saves PSD, while Illustrator and CorelDRAW are vector and save AI and CDR.

The correct answer is B, SVG. Scalable Vector Graphics stores a picture as mathematical descriptions of lines, curves and shapes written in XML, so the browser redraws it at whatever size is asked for and the edges stay perfectly sharp. That is why logos, maps and icons are kept as SVG. Option A, PNG, is a raster format: it is a grid of pixels, excellent for lossless images with transparency, but it blurs when enlarged. Option C, TIFF, is also raster and is favoured in scanning and printing because it can hold very high bit depths. Option D, BMP, is the plainest raster format of all, storing pixels with little or no compression. The examinable distinction is that raster images are made of pixels and pixelate, while vector images are made of paths and scale freely.

The correct answer is A, size of an object. In computer graphics the three basic two-dimensional transformations are translation, rotation and scaling. Scaling multiplies the coordinates of every point of an object by a scale factor, so the object grows when the factor is greater than one and shrinks when it lies between zero and one; uniform scaling uses the same factor along both axes and so changes the size without changing the proportions. Option B describes translation, which adds a fixed displacement to each coordinate and moves the object without resizing it. Option C is wrong for uniform scaling, since a square scaled equally in both directions is still a square; distortion of shape belongs to shearing or to unequal scaling. Option D is wrong because a single scaling matrix does not move an object's reference point in the way translation does.

The correct answer is C, CMYK. CMYK stands for cyan, magenta, yellow and key or black, and it is a subtractive model: the inks sit on white paper and subtract wavelengths from the light falling on it, so adding all of them together moves the result towards black. Option A, RGB, is the additive model of red, green and blue light used by monitors, projectors, cameras and scanners, where all three at full strength give white. Option B, HSB, is a way of describing a colour by hue, saturation and brightness that artists find convenient, but it is not a printing model. Option D, YUV, separates brightness from colour information and is used in video transmission to save bandwidth. The examiner's favourite one line is that screens are additive RGB and print is subtractive CMYK.

The correct answer is B, instructions telling an instrument what to play. MIDI stands for Musical Instrument Digital Interface, a standard of the early nineteen eighties by which synthesisers, keyboards and computers exchange messages about which note begins, how hard it is struck, how long it lasts and which instrument voice should sound. Because only these instructions are stored, a MIDI file is tiny compared with recorded audio, and the same file can sound quite different on two synthesisers. Option A describes a waveform format such as WAV, which samples the actual air pressure of a performance. Option C belongs to formats such as MP4 or AVI. Option D is wrong because MIDI carries no picture at all, and printed scores come from notation software. Remember the contrast: WAV records sound, MIDI records the performance's instructions.

The correct answer is C, 256. The number of colours a pixel can hold is two raised to the power of its bit depth, so eight bits give two to the eighth, that is 256 possible values. This is exactly the palette limit of the GIF format and of the older 256 colour display modes. Option A simply repeats the number of bits and is the commonest careless choice. Option B, 64, would be the count for six bits, not eight. Option D, 16,777,216, is the count for twenty-four bit true colour, in which eight bits each are given to red, green and blue, and it is the figure an examiner pairs with the phrase true colour. Candidates should memorise the small ladder: one bit two colours, four bits sixteen colours, eight bits 256 colours, sixteen bits 65,536 colours and twenty-four bits about 16.7 million colours.

The correct answer is C, Blender. Blender is a free and open-source suite in which an artist builds three dimensional models, applies materials and lighting, animates them along a timeline and then renders the frames into a finished image or film; it also carries sculpting, simulation and video editing tools. Option A, Audacity, is a free sound editor and recorder and handles no pictures at all. Option B, Inkscape, is free as well but works in two dimensions, drawing vector artwork in the SVG format. Option D, CorelDRAW, is proprietary paid software for two dimensional vector illustration and page layout, so it fails both halves of the question. For the exam, group the free tools together as GIMP for raster images, Inkscape for vector drawings, Audacity for sound and Blender for three dimensional animation.

The correct answer is C, PNG. Portable Network Graphics applies the deflate algorithm, which rearranges and encodes the pixel data without discarding any of it, so the decompressed image is identical to the original, pixel for pixel; it also supports an alpha channel for partial transparency. Option A, JPEG, is deliberately lossy, dropping fine detail in blocks of the image to reach small file sizes, and repeated saving degrades the picture further. Option B, MP3, is lossy in the same spirit for sound, removing what the ear is unlikely to notice. Option D, MPEG video, is lossy both within a frame and between frames, since it stores only the changes from one frame to the next. Keep the two lists apart: lossy means JPEG, MP3 and MPEG, while lossless means PNG, GIF, TIFF without compression, FLAC and ZIP.