Fundamentals of Multimedia

Transcription

1 Fundamentals of Multimedia 2 nd Edition 2014 Ze-Nian Li Mark S. Drew Jiangchuan Liu Chapter 2 : A Taste of Multimedia 1

2 Content: 2-1: Multimedia Tasks and Concerns? 2-2: Multimedia Presentation. 2-3: Data Compression 2-4: Multimedia Production 2-5: Multimedia Sharing and Distribution 2-6: Some Useful Editing and Authoring Tools 2

3 Objectives: This chapter introduces: a set of tasks and concerns that are considered in studying multimedia. issues in multimedia production and presentation are discussed 3

4 2.1 Multimedia Tasks and Concerns Multimedia content is ubiquitous in software all around us, including in our phones. We are interested in making interactive applications (or presentations ), using: Video editors such as Adobe Premiere or Cyberlink PowerDirector, Still-image editors such as Adobe Photoshop in the first instance, but then combining the resulting resources into interactive programs by making use of authoring tools such as Flash and Director that can include sophisticated programming. 4

5 2.2 Multimedia Presentation Now we briefly outline some effects to keep in mind for presenting multimedia, And Some useful guidelines for content design. 5

6 2.2 Multimedia Presentation Graphics Styles Careful thought has gone into combinations of color schemes and how lettering is perceived in a presentation. When constructing presentation then the Human visual dynamics should be considered. Human visual dynamics :As soon as the eye moves (saccades) it readjusts its exposure both chemically and geometrically by adjusting the iris which regulates the size of the pupil. Assig me t: define in more detail what is Human Visual Dynamics. (Optio a ) 6

7 2.2 Multimedia Presentation Color Principles and Guidelines (See figure i ext s ide) Some co or schemes a d art sty es are best combi ed ith a certai theme or sty e. Color schemes could be, for example, natural and floral for outdoor scenes and solid colors for indoor scenes. Examples of art styles are oil paints, watercolors, colored pencils, and pastels. A general hint is to not use too many colors, as this can be distracting. It helps to be consistent with the use of color. Then color can be used to signal changes in theme. 7

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9 2.2 Multimedia Presentation Fonts For effective visual communication: large fonts (18 to 36 points) are best, with no more than six to eight lines per screen. sans serif (Arial) fonts work better than serif (Times New Roman) fonts (serif fonts are those with short lines stemming from and at an angle to the upper and lower ends of a letter s strokes). (See Figure i previous s ide.) Upper part is good, while bottom one is poor. (Why do you thi k?) Aria and Times Ne Roma are just examples of these two kinds of fonts. 9

10 2.2 Multimedia Presentation A Color Contrast Seeing the results of Vetter et al. s research, we constructed a small Visual Basic program to investigate how readability of text colors depends on color and the color of the background. (Figure on 2.2) 10

11 2.2 Multimedia Presentation A Color Contrast The simplest approach to making readable colors on a screen is to use the principal complementary color as the background for text. For color values in the range 0 1(or, effectively, 0 255), if the text color is some triple (Red, Green, Blue), or (R,G, B) for short, a legible color for the background is likely given by that color subtracted from the maximum: (R, G, B) (1 R, 1 G, 1 B) or (R, G, B) (255 R, 255 G, 255 B) 11

12 2.2 Multimedia Presentation There are now even online calculators that can help to get the color contrast, to choose best colors scheme for your presentation, such as this one: 12

13 2.2 Multimedia Presentation A Color Contrast Another way to make reasonable color on a screen is the color opposite Also if the text is bright, the background is dark, and vice versa. 13

14 2.2 Multimedia Presentation Figure 2.3 shows a color wheel, with opposite colors equal to (1 R, 1 G, 1 B). An artist s color wheel will not look the same, as it is based on feel rather than on an algorithm. In the traditional artist s wheel, for example, yellow is opposite magenta, instead of opposite blue as in Fig. 2.3, and blue is instead opposite orange. 14

15 2.2 Multimedia Presentation Sprite Animation Sprites are ofte used i a imatio. However, the basic idea of sprite animation is simple. See the Examp e o ext t o s ides. 15

16 2.2 Multimedia Presentation Sprite Animation Suppose we have produced an animation figure, as in Fig. 2.4a. Then it is a simple matter to create a 1-bit mask M, as in Fig.2.4b, black on white, and the accompanying sprite S, as in Fig. 2.4c. 16

17 2.2 Multimedia Presentation Sprite Animation Now we can overlay the sprite on a colored background B, as in Fig. 2.5a, by first ANDing B and M, then ORing the result with S, with the final result as in Fig.2.5e. 17

18 2.2 Multimedia Presentation Video Transitions Video transitions can be an effective way to indicate a change to the next section. Video transitions are sy tactic means to signal scene changes and often carry sema tic meaning. Many different types of transitions exist; the main types are: cuts, ipes, disso ves, fade-i s, fade-outs. 18

19 2.2 Multimedia Presentation Types of Transitions: A cut: carries out an abrupt change of image contents in two consecutive video frames from their respective clips. Or A cut is an abrupt, but usually trivial film transition from one sequence to another. It is the: simplest and most frequently used video transition. 19

20 2.2 Multimedia Presentation Types of Transitions: A wipe: is a replacement of the pixels in a region of the viewport with those from another video. 20

21 2.2 Multimedia Presentation Types of Transitions: A dissolve: replaces every pixel with a mixture over time of the two videos, gradually changing the first to the second. 21

22 2.2 Multimedia Presentation Types of Transitions: Fade-in. Fade-out. Assig me t: explain both. 1 Mark 22

23 2.3 Data Compression O e of the most evide t a d importa t cha e ges of usi g mu timedia is the ecessity to compress data. We need excellent and fast data compression in order to avoid such high data rates that cause problems for storage and networks. (See Next slide Table 2.1 for Uncompressed Video sizes) Ho much compressio is required? I effect, this depe ds o the app icatio, o the capabi ity of the vie i g computer a d disp ay, a d o the ba d idth (i bits per seco d) avai ab e to perhaps stream a d certai y to vie the decompressed resu t. In the ubiquitous JPEG image compression standard the amount of compression is controlled by a value Q in the range The quality of the resulting image is best for Q = 100 and worst for Q = 0. The more image compression is done, the worse the quality (Q) of that image is. 23

24 2.3 Data Compression 24

25 2.3 Data Compression Next slide Figure 2.9a shows an original, uncompressed image taken by a digital camera that allows full-accuracy images to be captured, with no data compression at all. In Fig. 2.9b,c that while Q = 75 and 25 are not terrible, if we insist on going down to a Quality Factor of Q = 5 we do end up with an unusable image Fig. 2.9d. 25

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28 2.3 Data Compression What is the best compression ratio for JPEG images and for MPEG video, while remaining reasonable quality? Assig me t 1 Mark how expensive image and video processing is in terms of processing in the CPU? Discuss i the c ass 28

29 2.4 Multimedia Production Multimedia production can easily involve a host of people with specialized skills: an art director, graphic designer, production artist, producer, project manager, writer, user interface designer, sound designer, videographer, and 3D and 2D animators, as well as programmers. 29

30 2.4 Multimedia Production During the production timeline: The programmer is involved when the project is about 40% complete, with a reasonable target for an alpha version (an early version that does not contain all planned features) being perhaps % complete. the design phase consists of: storyboarding, flowcharting, prototyping, and user testing, as well as a parallel production of media. Programming and debugging phases would be carried out in consultation with marketing, and the distribution phase would follow. Assig me t: describe what can be done in each part of the design phase. 1 Mark 30

31 2.5 Multimedia Sharing and Distribution Multimedia content, once produced, needs to be published and then shared among users: Optical disks USB Internet Consider YouTube, the most popular video sharing site over the Internet, as an example. A user can easily create a Google account and channel (as YouTube is now owned by Google), and then upload a video, which will be shared to everyone or to selected users. YouTube further enables titles and tags that are used to classify the videos and link similar videos together (shown as a list of related videos). Figure 2.10 on next slide. The link to this video can be fed into such other social networking sites such as Facebook or Twitter as well, potentially propagating to many users of interest in a short time 31

32 2.5 Multimedia Sharing and Distribution 32

33 2.5 Multimedia Sharing and Distribution 33

34 2.5 Multimedia Sharing and Distribution The Internet is reshaping traditional TV broadcasting, as well. In the UK, the BBC s iplayer has been successfully broadcasting high-quality TV programs to both TV subscribers and public Internet users with Adobe Flashplayer since In the US, CNBC, Bloomberg Television, and Showtime use live-streaming services. China, the largest I ter et Protoco TV (IPTV) market by subscribers (12.6 million) to date, is probably the most vigorous market. Internet Protocol Television (IPTV) is the de ivery of te evisio co te t over computer et orks based o the ogica I ter et Protoco (IP), rather tha through traditio a terrestria, sate ite, a d cab e te evisio formats. U ike do oaded media, IPTV offers the abi ity to stream the source media co ti uous y. 34

35 2.5 Multimedia Sharing and Distribution Users viewing habits are also changing Compelling content is the core foundation of any IPTV proposition, which remains true today; yet IPTV services are becoming highly personalized, integrated, portable, and on-demand. Most service providers are moving beyond basic video offerings toward richer user experiences, particularly with the support for multi-screen viewing across TVs, PCs, tablets, and smartphones. 35

36 2.6 Some Useful Editing and Authoring Tools Since the first step in creating a multimedia application is probably creation of interesting video clips, we start off with looking at a video editing tool: Premiere: video editing program that allows you to quickly create a simple digital video by assembling and merging multimedia components Director: complete environment for creating interactive movies and animation. Traditional animation is created by showing slightly different images over time. Flash: is a simple authoring tool that facilitates the creation of interactive movies. 36

37 2.6 Some Useful Editing and Authoring Tools 37

38 2.6 Some Useful Editing and Authoring Tools 38

39 2.6 Some Useful Editing and Authoring Tools 39

40 -Choose one of the previous programs or any multimedia software and take a quick tour on its basics. 40

41 End of Chapter 2 41

42 Kingdom of Saudi Arabia Ministry of Education Umm AlQura University Adam University College Computer Science Department المملكة العربية السعودية وزارة التعليم جامعة أم القرى الكلية الجامعية أضم قسم الحاسب اآللي This Summary is an Online Content from this Book: Ze-Nia Li a d Mark S Dre, Fu dame ta s of Mu timedia, 1/e, Pre tice-ha, 2004 It is edited for Multimedia Systems Course by: T.Mariah Sami Khayat Teacher Adam University College For Co tacti g: mskhayat@uqu.edu.sa 42