Information and communicationsOCTobathS
African Journal of Economic and Management Studies Vol. 4 No. 1, 2013 pp. 9-33 ? Emerald Group Publishing Limited 2040-0705 DOI 10.1108/20400701311303131
Information and communications OCTobathS technologies in the age of globalization
Challenges and opportunities for Africa -------------------------------- - Felix M. Edoho Institute for Entrepreneurship & Business Development, Lincoln University, Jefferson City, Missouri, USA Abstract Purpose - This paper aims to examine the challenges and opportunities for implementing ICTs in Africa. It identifies potential areas that ICTs can be targeted and implemented for maximum in the region, and offers an integrated framework that could help the region to coordinate various components and institutionalize ICTs in the economy. It is argued that Africa needs an integrated approach to leverage ICTs for socioeconomic development. Design/methodology/approach - The paper reviews African theoretical perspectives of ICTs. Synthesizing literature on African perspectives of ICTs, an integrated framework is developed to help provide a coherent focus for the implementation of ICTs in a holistic manner. Findings - Basic systems for leveraging ICTs for development in Africa are fragmented and uncoordinated. Critical physical infrastructure and human capacity do not work synergistically to effectively implement ICTs. Where the basic infrastructure exists, various components do not operate synergistically to engender optimal results. Practical implications - Ideas formulated in this study will be helpful to future researchers relative to how various ICT components could be systematized and managed to stimulate sustainable socioeconomic development and structural changes in Africa. The framework will help to guide policymakers to design and implement ICT-friendly policies and strategies. Originality/value - A systemic framework is developed to help policymakers in Africa to institutionalize ICTs in their economies.
Keywords Africa, Globalization, ICTs, Digital divide, Poverty alleviation, Socioeconomic development, Communication technologies Paper
type Research paper
1. I ntroduction Recent years have witnessed the intensification of globalization as well as diffusion and ubiquity of information and communications technologies (ICTs).
AJEMS 4,1 Concomitantly, there have been profound changes in various aspects of all societies (Castells, 1999, p. 2; Hodge and Miller, 1997, p. 2). Because the changes have been “wide in scope and dizzying in speed,” the ICT revolution has been termed a “technological tsunami” (ITU/Orbicom, 2005, p. 1). ICT has revolutionized the ways firms manufacture products and market goods and services; transformed how governments run bureaucracies; and altered how nation-states conduct diplomacy (Adesida, 2001; Oshikoya and Hussain, 1998; Menou and Taylor, 2006; Stienstra et al., 2007). The rapidity and scope of ICT-induced changes explain why many optimists assert that ours is a global information society (Menou and Taylor, 2006;
ICTs in the a of globalizatio 10 Stienstra et al., 2007). The World Summit on Information Society (WSIS) has defined information society as where:
[...]everyone can create, access, utilize and share information and knowledge, enabling individuals, communities and peoples to achieve their full potential and improve their quality of life in a sustainable manner (ITU, 2003, p. 4).
Paralleling this claim about
the
emergent
information
society is the
complementary notion that ours is a
knowledge economy - “where business models are more often driven by expertise and intellectual
capabilities and
based on networking, connecting and collaborating” (SIIA, 2008, p. 5). Castells (1999, p. 2)
postulated that the global economy is informational because the “capacity to generate relevant knowledge
and process information efficiently, is the main source of productivity and competitiveness for firms, regions and countries”.
Furthermore, ICTs have redefined global social
relations as well as challenged our normative understanding of time and space (Castells, 1999, 2000, 2004). Even as ICTs impact all aspects of societies
(Adera and Camara, 2003; Ulrich and Chacko, 2005),
they also present enormous challenges and
opportunities (Heeks, 1999; Pigato, 2001; Lawal, 2006)
. Cogburn and Adeya (1999, p. viii) note that
while the “challenges facing Africa
in the
information
economy are
daunting” there are also “many new ‘windows of opportunity’ for Africa in the age of
globalization and the information economy”.
This article examines the challenges and opportunities relative to implementing ICTs in Africa in
the age of globalization. It focuses on identifying specific areas that ICTs could be targeted and implemented to yield maximum benefits. In this
context, an integrated framework is provided to hopefully help guide African
countries to implement and institutionalize or embed
ICTs in their socioeconomic systems. It is imperative that various components of ICTs are integrated to work synergistically to drive positive outcomes. Over the
years, African countries have attempted to implement
science and technology (S&T) for development. Such
efforts have not succeeded mostly because various
components of S&T were often not well integrated and coordinated. Consequently, S&T are not well embedded
AJEMS 4,1 in the socioeconomic systems in Africa. This partly accounts for why the region remains mostly technologically backward on indices of ICTs (ITU, 2002,2004,2007). Africa has 15 percent of the global population, but boasts less than 1 percent of the global internet users (Dunphy, 2000; ITU, 2002, 2007). As the least “connected” region to the global information society (Akpan, 2000, 2003), Africa is “a lost continent of the information age” (Odedra-Straubb, 1993, p. 2) and therefore a forgotten continent.
Given Africa’s technological backwardness and the vulnerability of its economy in the age of globalization (Edoho, 1997), the debate is no longer whether ICTs are relevant to Africa, “but how ICT can be beneficial” (Walsham and Sahay, 2006, p. 1; Walsham et al., 2007, p. 317) to the region. Studies have identified impediments to effective implementation of ICTs in Africa (Adeyeye and Iweha, 2005; Adesida, 2001; Fuchs and Horak, 2007; Odedra-Straubb, 1993; Okiy, 2010). The Information for Development Program (Info Dev) provides a list of 17 impediments to implementing ICTs in developing countries. They include physical infrastructure, law and public policy, accessibility, trust, literacy/education, interoperability and costs (Ngulube, 2007). While national and organizational factors are commonly cited as constraining the ability of African countries to implement ICTs (Odedra-Straubb, 1993),
ICTs in the a of globalizatio
11 global factors are often ignored when, in fact, most of the technologies in Africa are transferred from the industrialized countries. It is sometimes assumed that ICTs transferred from industrialized countries would be appropriate and readily implementable in Africa; that ICTs need to be implemented in all sectors and at all levels of the society at the same time; and that acquisition of foreignICTequipmentwould, i 》so/acto ，landAfrica“atthecyber ElDorado”(Akpan, 2003, p. 268). Missing in this optimistic fix is the sheer lack of understanding that “[r]ealizing the poverty -reducing potential of ICT is not guaranteed” (Cecchini and Scott, 2003, p. 76) and that “bringing technology to a new local context implicitly involves cultural transfer” (Walsham etal., 2007, p. 319). Bada (2002) provides evidence from a longitudinal study of radical organization change related to the computerization and networking of branches in the Nigerian banking industry. Undue focus on acquisition of ICTs may actually displace appropriate endogenous technology. Although acquisition of ICT hardware is vital, there must be appropriate level of endogenous technical capabilities to implement, operate and maintain the systems. There is also a clear lack of specificity in the literature relative to the potential industrial sectors that ICTs need to be deliberately targeted to engender cumulative developmental impact in Africa. Resource constraints and heavy upfront investment requirements (Cogburn and Adeya, 1999, p. 13) are central issues in affordability and accessibility of ICTs in Africa. Lessons from India (Cecchini and Scott, 2003) demonstrates that African countries need to identify critical sectors and selectively target and implement ICTs. For example, they can target agriculture, health care, education and governance in their implementation of ICTs. While ICTs offers potential opportunities to enhance productivity in these areas and alleviate poverty, the major challenges facing Africa in the age of globalization revolve around affordability, accessibility and leveraging of ICTs for development. This article is organized into seven sections. Following this introduction, Section 2 locates the opportunities and challenges of implementing ICTs in Africa in the broader context of globalization; it also establishes the links between ICTs and globalization. Section 3 provides theoretical perspectives of ICTs in African context; Section 4 assesses the status of ICTs in
AJEMS 4,1 Africa and the growing digital divide; Section 5 o^ers an integrative framework to guide the institutionalization of ICTs in the region; Section 6 identifies specific areas for targeting and implementing the integrative framework of ICTs to promote sustainable development; and the last section draws policy conclusions from the study.
2. G lobalization and ICT revolution: opportunities and challenges Globalization is a “hotly contested” (Cogburn and Adeya, 1999; Kabamba, 2008, p. 1) and “embattled” (Omotola, 2010, p. 107) concept. Giddens (2000, p. 520) believes that globalization is a:
[...]reordering of time and distance in our lives. Our lives are [...] increasingly influenced by activities and events happening well away from the social context in which we carry on our day-to-day activities. Conditions of complex interconnectedness are reflected in McGrew f s (1992, p. 23) view of globalization in terms of a:
[...] multiplicity of linkages and interconnections between the states and societies which make up the modern world system. It describes the process by which events, decisions and
ICTs in the a
of globalizatio 12
activities in one part of the world can come to have significant consequences for individuals and communities in quite distant part of the globe.
Globalization is b elieved to have “accelerated compression of the contemporary world and the intensification of consciousness of the world as a whole” (Robertson, 1992, p. 18).
Most definitions of globalization connote the notions of integration, interconnection and interdependence. Globalization is a multidimensional construct encompassing cultural, economic, financial, institutional, political and social components (Edoho, 1997). Pieterse (2002, p. 1) argues that globalization is a package deal: [...]that includes informatization (application of information technology), flexibilization (changes in production and labor associated with post-Fordism), financialization (the growing importance of financial instruments and services) and deregulation or liberalization (unleashing market forces). Although globalization is not a new phenomenon (Lawal, 2006; Omotola, 2010), “ICT is spearheading the current stage of globalization” (Hajela, 2005, p. 7). According to Cogburn and Adeya (1999, p. v), “One characteristic of this current period of globalization is the emergence of a new techno-economic paradigm.” They argue that the current techno-economic paradigm driven by ICTs has dislodged the old techno-economic paradigm that was based on the conjuncture of fordism (moving assembly line) and taylorism (scientific management) that had hitherto driven the world economy (Cogburn and Adeya, 1999, p. 7).
Kabamba (2008, p. 5) notes that ICTs are the “backbone of globalization”； they play a central role in the “actualization of globalization” (Okiy, 2010); and ICTs and globalization are twin “phenomena deeply linked” (Ilharco, 2003, p. 1). Ostry and Nelson (1995, p.
24) use “techno-globalism” to explain ICT-induced globalization which, according to them, refers to the fact that TNCs are exploiting technology globally and gaining access to new technology around the world by increasingly diffusing R&D and intensifying collaboration. Castells (1999, p. 2) theorized that the globalization-based transformation has been driven by a “new technological paradigm based on [...] ICTs.” ICTs are both a necessity for globalization as well as the determinant of the possibility for the process of globalization (Lelliott et al., 2000). Global integration of markets, increasing cross-country social exchanges and
AJEMS 4,1 shrinkage of distance all have been facilitated by the phenomenal growth in ICTs (Omotola, 2010; Pigato, 2001).
Dominant views in the triad countries (East Asia, North America and Western Europe) are that globalization and ICTs are beneficent forces for all countries. Zembylas and Vrasidas (2005, p. 65) claim that “[g]lobalization and the use of ICT open up opportunities for promoting democracy and prosperity in poorer parts of the planet.”It is also believed that globalization will culminate in increased economic growth, higher income and standards of living, accelerated innovation and diffusion of technology, management knowledge and skills (Lawal, 2006). The assumption is that all countries would equally benefit from globalization and ICTs. The notion that globalization and ICTs are equalizers originates from the thinking that their benefits would accrue to all countries equitably or equally, even as it is well known that all countries are markedly unequal.
However, the dominant views of globalization and ICTs in many developing countries border on pessimism and they are diametrically opposed to the optimistic views of the triad countries. Caroline Thomas characterized globalization as a process
ICTs in the a of globalizatio 13
“by which the ideology of the dominant group, presented as universal, is used to legitimate the marginalization and neutralization of competing visions and values” (quoted in Akpan, 2003, p. 266). Those skeptical of the benefits of globalization and ICTs for Africa point out that increasing globalization and integration of the world economy have not resulted in corresponding diffusion of ICTs to the region. ITU (1998) indicated that:
[...]an inhabitant of a high-income country is four times more
likely to have access to a television set than an inhabitant of
low-income country; 25 times more likely to have access to a telephone; but almost 8,000 times more likely to have access
to an Internet host computer.
Such an info-gap
explains the increasing
marginalization of Africa in the age of globalization. Globalization puts Africa in a precarious situation in that 20 countries in the region have, per capita, an income lower than
20 years ago. Two-thirds of the least
developing countries are in Africa. Food-surplus 20
years ago, Africa is now plagued by food-deficit and dependent on
food aid. African scholars believe that
globalization is a new phase of neo-imperialism and ICTs are the tools of capitalist expansion rooted in
neoliberal economic policies that emphasize exploitation, accumulation, inequality and polarization (Lawal, 2006; Omotola, 2010).
Others have framed the ICT challenges facing Africa
in terms of contradictions manifested in the globalization process itself.
Edoho (1997, p. 2) elaborated the
tendencies by which globalization and the new world order “seek to simultaneously integrate the world
politically; fragment it economically; polarize it
technologically; and differentiate it regionally.” Akpan
(2003, p. 266) asserted that globalization is “a dialectical
process which
at once integrates and disintegrates
communities.” In the same vein, Amuwo (2003, p. 2)
remarked that globalization is “a complex process and phenomenon of antinomies and dialectics: integrating
and fragmenting
world; uniformity and localization;
increased material prosperity and deepening misery;
homogenization and hegemonization.” This discussion
of globalization is critical to our understanding that the revolutionary impact of globalization and ICTs
determines the “winners and losers of the information society” (Fuchs and Horak, 2007, p. 5). It sets a stage for the review of theoretical perspectives in the next section and to assess the status of ICTs in Africa in the
AJEMS 4,1 subsequent one. Before we do that, however, it is important to clarify the concepts of ICTs and development. For the purpose of this study, ICTs encompass a gamut of tools, devices, mechanisms and processes used in the creation, management, application, storage, retrieval and dissemination of data as well as in the generation and transmission of knowledge by electronic means (Heeks, 1999; Senn, 2004). Following Shapiro and Varian (1999, p. 3), “anything that can be digitized - encoded as a stream of bits - is information.” The three major components of ICTs are computers, telecommunication networks and know-how. ICTs are computer-mediated operations and activities made possible by the convergence of microelectronics, computing, telephony, fax, internet and telecommunications. Like globalization, the concept of development lacks a universally accepted definition. As Omotola (2010, p. 110) argues, the problem is not just because development is “both a multidimensional and a value loaded concept, but it is also due to current pluralism in the development literature.” It is broadly accepted that development encapsulates various dimensions and processes of positive changes in societies:
ICTs in the a
of globalizatio 14
economic, cultural, political and social. For example, UNECA (1996, p. 1) defines development as “an increase of knowledge and skills and creative potentials that can be applied to improve quality of life.” Todaro (1985) states that development connotes:
[...]a multidimensional process involving major changes in social structures, popular
attitudes and national institutions, as well as acceleration of economic growth, the reduction
of inequality and the eradication of absolute poverty.
Later, the author also identified certain core dimensions
of development (Todaro, 1989, pp. 89-90): ability to provide as many people as possible with their basic needs or ability to acquire adequate food, shelter, health care and protection. Implementing ICTs in the agriculture sector can help to enhance productivity and provide adequate food, which can also help to provide shelter and security as well as improve health. Development also involves the perception of individuals
or groups of self-worth and self-esteem as respected members of society.
Sen (1990, 1999) also sheds light on the idea of development. He conceptualizes development as the “capacity expansion” which is synonymous with freedom. As a capacity expansion, development entails significant enhancement and strengthening of individuals, state and the society. It also means empowerment of the institutional capacity of state for effective governance to provide enabling environment
for individuals to apply ICTs to meet their basic needs and self-fulfillment. Sen (1999) postulates that freedom
is not only the ultimate end; it is an effective means of development. The notion of development as a freedom speaks to the requirement for autonomy of individuals in determining their own future within the context political community (Omotola, 2010). Development also entails freedom in the sense that individuals and society have a range of choices relative to their material necessities for self-reproduction as well as the ability and opportunities
to have a say in how values are allocated (Sen, 1999).
To maximize the opportunities for a capacity expansion and freedom as key components of development, both individuals and states need tools. If development is the end-state, then ICTs are the means. ICTs can help individuals, groups and societies to expand and improve upon their production capacities to meet their basic needs and therefore guarantee
AJEMS 4,1 freedom from wants. For ICTs to succeed in playing such a vital role, they must be properly integrated and deeply embedded in the economic, political and social systems to help enhance the ability and expand the capacity of individuals to change their material conditions for the better. Globalization affects accessibility and affordability of ICTs and therefore impacts development. The linkages among globalization, ICTs and development are such that their impacts are mutually reinforcing.
3.T heoretical perspectives of ICTs in Africa
In order to identify specific areas that ICTs can be implemented in Africa to engender positive outcomes, it is important to understand the perspectives of them (ICTs) in the region. Also, it is imperative to note that due to the dehumanizing level of poverty in Africa, debate on ICTs in the region is often framed in terms of mutually exclusive binary propositions: “either bread or computer?” (Tongia et al.,2003), “food or phone?” Bill Gates, the CEO of Microsoft and software guru, is quoted to hav e said that “people need healthcare not laptops” (Royce, 2001). Ted Turner, the founder of CNN, has stated that:
ICTs in the a of globalizatio 15
We talk about the digital divide [...] all the time at Time-Warner too. We want to get computer to everyone J s hands. But half the people in the world don J t have electricity. Over a billion don J t have access to clean drinking water. Forget the digital divide, they need food, water, clothing, shelter and a chance for education (Fuchs and Horak, 2007, p. 28).
Framing the discourse in almost mutually exclusive
terms, some assert that because Africa comprises 34 of the 50 poorest countries in the world, ICTs are the least of the
myriad problems facing the region struggling to
meet existential needs of its citizens (Akpan, 2000; Jegede, 1995). By contrast, others contend that Africa
needs ICTs to combat poverty (Pigato, 2001;
UNECA, 1996). Heeks (1999) offers a framework of ICTs from
two continua. First, a continuum of “technology impacts ”： from optimism to pessimism.
Optimists
associate ICTs
mostly with positive impacts, while
pessimists associate them with negative impacts. Second, a continuum
of “impact cause ”： from
technological determinism to social determinism.
Proponents of technological determinism believe that the attributes of technology determine the impacts of
introducing ICTs, while advocates of social determinism argue that
human choices within the social systems actually determine the impacts of introducing ICTs in
society. In the African context which is the primary focus of this article, these contrasting views of ICTs can be
called techno-pessimism and techno-optimism. 3.1 Perspective of techno-pessimism
Techno-pessimism is based on the profound doubts that ICTs are development priorities in Africa. It argues that ICTs rank the lowest among the myriad
problems plaguing Africa.
The perspective notes that Africa is
threatened by abject poverty, food deficit, chronic
malnutrition and ravaged
by the HIV/AIDS epidemics.
Techno-pessimists contend that Africa must focus
efforts on alleviating these dehumanizing conditions, rather than embarking upon a wild goose chase of ICTs. Those who subscribe to techno-pessimistic perspective ask poignantly whether it is: [...]appropriate for African leaders to ignore the basic needs of their people and hop onto the bandwagon of the [ICTs]? Will acquisition of new communication
technologies transform African economies, lead to
greater food production and improved quality of life, health and housing, overcome poverty and illiteracy and end internecine civil strife? (Obijiofor, 1997).
AJEMS 4,1 Techno-pessimists believe that investment in ICTs would deprive Africa of the resources needed for food production, education and healthcare. They assert that it is foolhardy for a region that depends heavily on food aid to romanticize with ICTs and that ICTs would not feed empty stomachs; treat the sick; or enhance quality of life. Techno-pessimists believe that the unwarranted focus on ICTs tends to divert attention from the urgent needs of the masses. Jegede (1995, p. 221) states that: If[...] everyone in Africa is electronically networked today, it would not necessarily develop Africa. In fact, what it would do and appears to be doing at the moment, is divert attention from all other problems of development making people believe that getting hooked to the superhighway is the panacea for Africa’s problems. The perspective further observes that Africa lacks the basic infrastructure for implementing and sustaining ICTs: power/electricity, telephone and telecommunication systems. Where there is a modicum of ICT infrastructure in African countries, it is concentrated in a few urban areas where less than 20 percent of the population live and work. Given the high rate of illiteracy compounded by abject poverty in Africa,
ICTs in the a
of globalizatio 16
techno-pessimists maintain that ICTs are urban projects intended to further drain the limited resources from basic need programs for the masses to benefit a small elite class:
Three quarters of Africa J s population is illiterate (so hooking them to the Internet is out of question); three quarters of Africa is rural without basic facilities of electricity and telephone (so hooking them to the Internet can only be restricted to the urban areas); three quarters of universities in Africa have depleted library resources, have overworked academics and run computer science department without computers [...] and there are currently 200 million personal computers world-wide but less than 1 percent of them are located in Africa (Jegede, 1995, p. 221).
Finally, techno-pessimists claim further that as globalization aggravates the existing geospatial stratification and differentiation, ICTs would further accentuate urban-rural and rich-poor chasm in Africa. They fear that ICTs will even “exacerbate existing disparities based on location, gender, ethnicity, age and especially, income level and between ‘rich f and ‘poor f countries” (https://www.docsj.com/doc/ca16344678.html,, 2001). Akin to this is an understanding that ICT contents developed in the socioeconomic context of industrialized countries are grossly inappropriate for Africa. Ngwainmbi (2000, pp. 538-41) is not alone in arguing that ICTs, particularly the internet, is a form of electronic colonization that undermines and suppresses local culture and social norms by promoting Western language and values.
3.2 Perspective of techno-optimism
Techno-optimism is predicated on the notion that in view of globalization, Africa cannot do without ICTs. This perspective is touted by many international organizations, non-governmental organizations and multilateral agencies, including the World Bank and United Nations. Fleming (1996, p. 1) noted that: [...] [t]he message of all institutions and other organizations involved in development programs emphasizes the urgency of providing Africa with ways to enter and participate in the world economy, where information and communication technologies are a factor of economic development.
In 1995, the World Bank theorized that “information revolution offers Africa a dramatic opportunity to leapfrog into the future, breaking out of decades of stagnation or decline.” Apocalyptically, it warned that: Africa must seize this opportunity, quickly. If African countries cannot take advantage of the information revolution and surf
AJEMS 4,1
this great wave of technological change, they may be crushed
by it (Royce, 2001).
Similarly, in a 1999 study captioned “Can Sub-Saharan Africa Claim the 21st Century?” then World Bank President, James Wolfenson, stated in the preface that “information and communication technology offers enormous opportunities for Africa to leap frog stages of development” (Etta and Pavyn-Wamahiu, 2003, p. 2). Furthermore, the UNECA (1996) has warned that the consequence of the failure to utilize ICTs in Africa is “as negative as the refusal to attend school. It is a choice between being left out or benefiting from enormous benefits of information technology”.
Former UN Secretary General Annan (1999, p. 1079) stated that:
[...]the Internet holds the greatest promise humanity has known
for long-distance learning and universal access to quality education [...] It offers the best chance yet for developing
ICTs in the a of globalizatio 17
countries to take their rightful place in the global economy [...] And so our mission must be to ensure access as widely as possible. If we do not, the gulf between the haves and the have-nots will be the gulf between the technology-rich and technology-poor. The optimism that “ICT [...] presents opportunity for developing countries and countries with economies in transition to drastically improve their economies” (Haleja, 2005, p. 4) stems from the idea that ICTs would alleviate poverty and foster development in Africa. President Ellen Johnson-Sirleaf of Liberia states that “If any field of endeavor has been touted as [having] the possibilities of doing much [for Africa], it is the field of information and communication technology” (Manu, 2006, p. 3). Techno-optimists assert that because global economy is knowledge-based and information-driven, ICTs offer opportunities that poor countries need to participate in it. They argue that access to ICTs is critical to conquering poverty and empowering the poor (Pigato, 2001). Even if they were to agree with the techno-pessimists that ICTs would not usher in development in the short-run, however, techno-optimists question whether “the poor should, in addition to the existing deprivation of income, food and health service, etc. also be further deprived of new opportunities to improve their livelihood?” (Weigel and Waldburger, quoted in Tongia et al., 2003, p. 22). ICT-based development thesis asserts that poor countries can leapfrog towards a sustainable future. Leapfrogging is the notion that developing countries would advance from a condition of “zero” or “limited” ICTs to widespread adoption and diffusion of sophisticated technologies (Pigato, 2001). Technolog ical leapfrogging means “implementation of a new and up-to-date technology in an application area in which at least the previous version of that technology has not been deployed” (Davidson etal., 2002, p. 2). For example, while many households in Africa never had even a single telephone land line, many of them now have access to or own cellular phones. Advocacy for ICT-based development in Africa is rooted firmly in the belief that those who control technology in this age of globalization also control the lever of power. Olivier Coeur De Roy contends that ICTs are not a luxury but imperative for Africa, because they comprise certain tangible stakes that Africa can only ignore at its own peril: power, economic, technological and research. According to him:
AJEMS 4,1 [...]technological developments in networking and communication infrastructure are not a luxury, they are a priority for Africa as they comprise considerable and tangible stakes: stakes of power, because nowadays being on the information highway gives power; economic stakes because of the huge investments involved with new information technologies; technological stakes in the choices being made over infrastructure and methods of connection in Africa; and stakes in the research sector to develop new information technologies according to the priorities, needs and expectations of the African continent (De Roy, 1997, p. 892). The attention of African countries is also drawn to the emerging global ICT-based architecture of geopolitical influence and hegemonic power. Balakrishnan (2001, p. 966) hypothesized that “Countries that master the techniques of creating, managing and protecting their knowledge and information products would emerge as the superpowers in the ensuing knowledge era.” Techno-pessimistic and techno-optimistic views of ICTs differ fundamentally in terms of what should be development priorities in Africa. The two perspectives of ICTs have their merits and demerits. By framing the debate in binary terms, techno-pessimists suggest that investing in ICTs and basic needs is mutually exclusive. This is
AJEMS 4,1
18 a reductionist view of development that begins and ends with basic needs. Yet, ICTs and basic needs are inextricably linked. As indicated previously, development goes beyond meeting the material basic needs and includes capacity expansion and freedom (Sen, 1999). In the age of globalization and ICT revolution, basic needs would include affordability and accessibility of information by the poor to expand their productive capacity, meet their basic needs and enh ance their freedom. In fact “[t]he debate in the 1990s over choosing between ICT and other development imperatives has now been shifted from one of tradeoff to one of complementarity” (Markle Foundation/Accenture/UNDP, quoted in Tongia etal., 2003, p. 18).
By sharp contrast, techno-optimists present ICTs as the panaceas for all the problems in Africa. They often make sweeping claims about the efficacy of ICTs and their developmental utility. “If the poor are considered overtly at all, the feeling is that they must gain eventually from adopting technology because technology is development” (Heeks, 1999, p. 12). Pigato (2001, p. 8) notes that within “the optimistic view” tends to overstate the importance of ICTs for addressing the real information needs of the poor. Implicit in this view is the notion of automaticity: once ICT machine and equipment are installed, development occurs automatically - that is, the basic needs of the poor are met; their capacity is enhanced; and their freedom is secured:
Yet the “ICT fetishists” have so far been unable to demonstrate how ICT-based information represents a more important resource than water, food, land, shelter, production technology, money, skills or power in the development process (Heeks, 1999, p. 16).
Techno-optimistic approach ignores the fact that other factors, such as public policies, technological infrastructure and endogenous capabilities, must be present in the society for effective implementation of ICTs to occur. Also, they do not account for why ICT projects in Africa have been unsuccessful. Lucas (2005, p. 5) has argued that the key to success with technology is not the technology per se but the ability to manage it well.
4.S tatus of ICTs in Africa and global digital divide The magnitude of diffusion and pervasiveness of ICTs in a social system produces information
economy/society. Thus, Castells (1999, p. 2) asserts that the global economy is informational because the “capacity to generate relevant knowledge and process information efficiently, is the main source of productivity and competitiveness for firms, regions and countries.” The WSIS defines information society as where: [...]everyone can create, access, utilize and share information and knowledge, enabling individuals, communities and peoples to achieve their full potential and improve their quality of life in a sustainable manner (ITU, 2003, p. 4).
Hajela (2005) enumerates the features of information society/economy: a highly developed ICT infrastructure, equitable and ubiquitous access to ICTs, appropriate contents in suitable formats; and effective communication. He indicates that the presence of these features would enable “individuals, corporate entities and communities to achieve their full potential, promote sustainable economic and environmental development, improve quality of life and alleviate poverty, hunger and social exclusion” (Hajela, 2005, p. 18). Akin to the claims about information economy/society is the notion that ours is a knowledge economy - “where business models are more often driven by expertise and intellectual capabilities and based on networking, connecting and collaborating” (SIIA, 2008, p. 5).
交互式多模型算法仿真与分析
硕037班 刘文3110038020 2011/4/20交互式多模型仿真与分析IMM算法与GBP算法的比较，算法实现和运动目标跟踪仿真，IMM算法的特性分析 多源信息融合实验报告
交互式多模型仿真与分析 一、 算法综述 由于混合系统的结构是未知的或者随机突变的，在估计系统状态参数的同时还需要对系统的运动模式进行辨识，所以不可能通过建立起一个固定的模型对系统状态进行效果较好的估计。针对这一问题，多模型的估计方法提出通过一个模型集{}(),1,2,,j M m j r == 中不同模型的切换来匹配不同目标的运动或者同一目标不同阶段的运动，达到运动模式的实时辨识的效果。 目前主要的多模型方法包括一阶广义贝叶斯方法（BGP1），二阶广义贝叶斯方法（GPB2）以及交互式多模型方法等（IMM ）。这些多模型方法的共同点是基于马尔科夫链对各自的模型集进行切换或者融合，他们的主要设计流程如下图： M={m1,m2,...mk} K 时刻输入 值的形式 图一 多模型设计方法 其中，滤波器的重初始化方式是区分不同多模型算法的主要标准。由于多模型方法都是基于一个马尔科夫链来切换与模型的，对于元素为r 的模型集{}(),1,2,,j M m j r == ，从0时刻到k 时刻，其可能的模型切换轨迹为 120,12{,,}k i i i k trace k M m m m = ，其中k i k m 表示K-1到K 时刻，模型切换到第k i 个， k i 可取1,2,,r ，即0,k trace M 总共有k r 种可能。再令1 2 1 ,,,,k k i i i i μ+ 为K+1时刻经由轨迹0,k trace M 输入到第1k i +个模型滤波器的加权系数，则输入可以表示为 0,11 2 1 12|,,,,|,,,???k k trace k k k i M k k i i i i k k i i i x x μ++=?∑ 可见轨迹0,k trace M 的复杂度直接影响到算法计算量和存储量。虽然全轨迹的
五种大数据压缩算法
?哈弗曼编码 A method for the construction of minimum-re-dundancy codes, 耿国华1数据结构1北京:高等教育出版社,2005:182—190 严蔚敏,吴伟民.数据结构(C语言版)[M].北京:清华大学出版社,1997. 冯桂,林其伟,陈东华.信息论与编码技术[M].北京:清华大学出版社,2007. 刘大有,唐海鹰,孙舒杨,等.数据结构[M].北京:高等教育出版社,2001 ?压缩实现 速度要求 为了让它(huffman.cpp)快速运行，同时不使用任何动态库，比如STL或者MFC。它压缩1M数据少于100ms（P3处理器，主频1G）。 压缩过程 压缩代码非常简单，首先用ASCII值初始化511个哈夫曼节点： CHuffmanNode nodes[511]; for(int nCount = 0; nCount < 256; nCount++) nodes[nCount].byAscii = nCount; 其次，计算在输入缓冲区数据中，每个ASCII码出现的频率： for(nCount = 0; nCount < nSrcLen; nCount++) nodes[pSrc[nCount]].nFrequency++; 然后，根据频率进行排序： qsort(nodes, 256, sizeof(CHuffmanNode), frequencyCompare); 哈夫曼树，获取每个ASCII码对应的位序列： int nNodeCount = GetHuffmanTree(nodes); 构造哈夫曼树 构造哈夫曼树非常简单，将所有的节点放到一个队列中，用一个节点替换两个频率最低的节点，新节点的频率就是这两个节点的频率之和。这样，新节点就是两个被替换节点的父
LZ77压缩算法实验报告
LZ77压缩算法实验报告 一、实验内容 使用C++编程实现LZ77压缩算法的实现。 二、实验目的 用LZ77实现文件的压缩。 三、实验环境 1、软件环境：Visual C++ 6.0 2、编程语言：C++ 四、实验原理 LZ77 算法在某种意义上又可以称为“滑动窗口压缩”，这是由于该算法将一个虚拟的，可以跟随压缩进程滑动的窗口作为术语字典，要压缩的字符串如果在该窗口中出现，则输出其出现位置和长度。使用固定大小窗口进行术语匹配，而不是在所有已经编码的信息中匹配，是因为匹配算法的时间消耗往往很多，必须限制字典的大小才能保证算法的效率；随着压缩的进程滑动字典窗口，使其中总包含最近编码过的信息，是因为对大多数信息而言，要编码的字符串往往在最近的上下文中更容易找到匹配串。 五、LZ77算法的基本流程 1、从当前压缩位置开始，考察未编码的数据，并试图在滑动窗口中找出最长的匹 配字符串，如果找到，则进行步骤2，否则进行步骤3。 2、输出三元符号组( off, len, c )。其中off 为窗口中匹
配字符串相对窗口边 界的偏移，len 为可匹配的长度，c 为下一个字符。然后将窗口向后滑动len + 1 个字符，继续步骤1。 3、输出三元符号组( 0, 0, c )。其中c 为下一个字符。然后将窗口向后滑动 len + 1 个字符，继续步骤1。 六、源程序 /********************************************************************* * * Project description: * Lz77 compression/decompression algorithm. * *********************************************************************/ #include 实验名称：LZSS压缩算法实验报告 一、实验内容 使用Visual 6..0 C++编程实现LZ77压缩算法。 二、实验目的 用LZSS实现文件的压缩。 三、实验原理 LZSS压缩算法是词典编码无损压缩技术的一种。LZSS压缩算法的字典模型使用了自适应的方式，也就是说，将已经编码过的信息作为字典， 四、实验环境 1、软件环境：Visual C++ 6.0 2、编程语言：C++ 五、实验代码 #include -- need byte-swap function for big endian CPU */ #define READ_LE32(X) *(uint32_t *)(X) #define WRITE_LE32(X,Y) *(uint32_t *)(X) = (Y) /* this assumes sizeof(long)==4 */ typedef unsigned long uint32_t; /* text (input) size counter, code (output) size counter, and counter for reporting progress every 1K bytes */ static unsigned long g_text_size, g_code_size, g_print_count; /* ring buffer of size N, with extra F-1 bytes to facilitate string comparison */ static unsigned char g_ring_buffer[N + F - 1]; /* position and length of longest match; set by insert_node() */ static unsigned g_match_pos, g_match_len; /* left & right children & parent -- these constitute binary search tree */ static unsigned g_left_child[N + 1], g_right_child[N + 257], g_parent[N + 1]; /* input & output files */ static FILE *g_infile, *g_outfile; /***************************************************************************** initialize trees *****************************************************************************/ static void init_tree(void) { unsigned i; /* For i = 0 to N - 1, g_right_child[i] and g_left_child[i] will be the right and left children of node i. These nodes need not be initialized. Also, g_parent[i] is the parent of node i. These are initialized to NIL (= N), which stands for 'not used.' For i = 0 to 255, g_right_child[N + i + 1] is the root of the tree for strings that begin with character i. These are initialized to NIL. Note there are 256 trees. */ for(i = N + 1; i <= N + 256; i++) g_right_child[i] = NIL; for(i = 0; i < N; i++) g_parent[i] = NIL; } /***************************************************************************** Inserts string of length F, g_ring_buffer[r..r+F-1], into one of the trees (g_ring_buffer[r]'th tree) and returns the longest-match position and length via the global variables g_match_pos and g_match_len. If g_match_len = F, then removes the old node in favor of the new one, because the old one will be deleted sooner. 多媒体数据压缩实验报告 篇一：多媒体实验报告_文件压缩 课程设计报告 实验题目：文件压缩程序 姓名：指导教师：学院：计算机学院专业：计算机科学与技术学号： 提交报告时间：20年月日 四川大学 一，需求分析： 有两种形式的重复存在于计算机数据中，文件压缩程序就是对这两种重复进行了压 缩。 一种是短语形式的重复，即三个字节以上的重复，对于这种重复，压缩程序用两个数字：1.重复位置距当前压缩位置的距离；2.重复的长度，来表示这个重复，假设这两个数字各占一个字节，于是数据便得到了压缩。 第二种重复为单字节的重复，一个字节只有256种可能的取值，所以这种重复是必然的。给 256 种字节取值重新编码，使出现较多的字节使用较短的编码，出现较少的字节使用较长的编码，这样一来，变短的字节相对于变长的字节更多，文件的总长度就会减少，并且，字节使用比例越不均 匀，压缩比例就越大。 编码式压缩必须在短语式压缩之后进行，因为编码式压缩后，原先八位二进制值的字节就被破坏了，这样文件中短语式重复的倾向也会被破坏（除非先进行解码）。另外，短语式压缩后的结果：那些剩下的未被匹配的单、双字节和得到匹配的距离、长度值仍然具有取值分布不均匀性，因此，两种压缩方式的顺序不能变。 本程序设计只做了编码式压缩，采用Huffman编码进行压缩和解压缩。Huffman编码是一种可变长编码方式，是二叉树的一种特殊转化形式。编码的原理是：将使用次数多的代码转换成长度较短的代码，而使用次数少的可以使用较长的编码，并且保持编码的唯一可解性。根据 ascii 码文件中各 ascii 字符出现的频率情况创建 Huffman 树，再将各字符对应的哈夫曼编码写入文件中。同时，亦可根据对应的哈夫曼树，将哈夫曼编码文件解压成字符文件. 一、概要设计： 压缩过程的实现: 压缩过程的流程是清晰而简单的: 1. 创建 Huffman 树 2. 打开需压缩文件 3. 将需压缩文件中的每个 ascii 码对应的 huffman 编码按 bit 单位输出生成压缩文件压缩结束。 价值工程 置，是一项十分有意义的工作。另外恶意代码的检测和分析是一个长期的过程，应对其新的特征和发展趋势作进一步研究，建立完善的分析库。 参考文献： [1]CNCERT/CC.https://www.docsj.com/doc/ca16344678.html,/publish/main/46/index.html. [2]LO R,LEVITTK,OL SSONN R.MFC:a malicious code filter [J].Computer and Security,1995,14(6):541-566. [3]KA SP ER SKY L.The evolution of technologies used to detect malicious code [M].Moscow:Kaspersky Lap,2007. [4]LC Briand,J Feng,Y Labiche.Experimenting with Genetic Algorithms and Coupling Measures to devise optimal integration test orders.Software Engineering with Computational Intelligence,Kluwer,2003. [5]Steven A.Hofmeyr,Stephanie Forrest,Anil Somayaji.Intrusion Detection using Sequences of System calls.Journal of Computer Security Vol,Jun.1998. [6]李华,刘智,覃征,张小松.基于行为分析和特征码的恶意代码检测技术[J].计算机应用研究，2011，28（3）：1127-1129. [7]刘威，刘鑫，杜振华.2010年我国恶意代码新特点的研究.第26次全国计算机安全学术交流会论文集，2011，（09）. [8]IDIKA N,MATHUR A P.A Survey of Malware Detection Techniques [R].Tehnical Report,Department of Computer Science,Purdue University,2007. 0引言 现有的压缩算法有很多种，但是都存在一定的局限性，比如：LZw [1]。主要是针对数据量较大的图像之类的进行压缩，不适合对简单报文的压缩。比如说，传输中有长度限制的数据，而实际传输的数据大于限制传输的数据长度，总体数据长度在100字节左右，此时使用一些流行算法反而达不到压缩的目的，甚至增大数据的长度。本文假设该批数据为纯数字数据，实现压缩并解压缩算法。 1数据压缩概念 数据压缩是指在不丢失信息的前提下，缩减数据量以减少存储空间，提高其传输、存储和处理效率的一种技术方法。或按照一定的算法对数据进行重新组织，减少数据的冗余和存储的空间。常用的压缩方式[2,3]有统计编码、预测编码、变换编码和混合编码等。统计编码包含哈夫曼编码、算术编码、游程编码、字典编码等。 2常见几种压缩算法的比较2.1霍夫曼编码压缩[4]：也是一种常用的压缩方法。其基本原理是频繁使用的数据用较短的代码代替，很少使用 的数据用较长的代码代替，每个数据的代码各不相同。这些代码都是二进制码，且码的长度是可变的。 2.2LZW 压缩方法[5,6]：LZW 压缩技术比其它大多数压缩技术都复杂，压缩效率也较高。其基本原理是把每一个第一次出现的字符串用一个数值来编码，在还原程序中再将这个数值还成原来的字符串，如用数值0x100代替字符串ccddeee"这样每当出现该字符串时，都用0x100代替，起到了压缩的作用。 3简单报文数据压缩算法及实现 3.1算法的基本思想数字0-9在内存中占用的位最 大为4bit ， 而一个字节有8个bit ，显然一个字节至少可以保存两个数字，而一个字符型的数字在内存中是占用一个字节的，那么就可以实现2:1的压缩，压缩算法有几种，比如，一个自己的高四位保存一个数字，低四位保存另外一个数字，或者，一组数字字符可以转换为一个n 字节的数值。N 为C 语言某种数值类型的所占的字节长度，本文讨论后一种算法的实现。 3.2算法步骤 ①确定一种C 语言的数值类型。 —————————————————————— —作者简介：安建梅（1981-），女，山西忻州人，助理实验室，研究方 向为软件开发与软交换技术；季松华（1978-），男，江苏 南通人，高级软件工程师，研究方向为软件开发。 数据快速压缩算法的研究以及C 语言实现 The Study of Data Compression and Encryption Algorithm and Realization with C Language 安建梅①AN Jian-mei ；季松华②JI Song-hua （①重庆文理学院软件工程学院，永川402160；②中信网络科技股份有限公司，重庆400000）（①The Software Engineering Institute of Chongqing University of Arts and Sciences ，Chongqing 402160，China ； ②CITIC Application Service Provider Co.，Ltd.，Chongqing 400000，China ） 摘要：压缩算法有很多种，但是对需要压缩到一定长度的简单的报文进行处理时，现有的算法不仅达不到目的，并且变得复杂， 本文针对目前一些企业的需要，实现了对简单报文的压缩加密，此算法不仅可以快速对几十上百位的数据进行压缩，而且通过不断 的优化，解决了由于各种情况引发的解密错误，在解密的过程中不会出现任何差错。 Abstract:Although,there are many kinds of compression algorithm,the need for encryption and compression of a length of a simple message processing,the existing algorithm is not only counterproductive,but also complicated.To some enterprises need,this paper realizes the simple message of compression and encryption.This algorithm can not only fast for tens of hundreds of data compression,but also,solve the various conditions triggered by decryption errors through continuous optimization;therefore,the decryption process does not appear in any error. 关键词：压缩；解压缩；数字字符；简单报文Key words:compression ；decompression ；encryption ；message 中图分类号：TP39文献标识码：A 文章编号：1006-4311（2012）35-0192-02 ·192· 压缩编码算法设计与实现实验报告 一、实验目的：用C语言或C++编写一个实现Huffman编码的程序，理解对数据进行无损压缩的原理。 二、实验内容：设计一个有n个叶节点的huffman树，从终端读入n个叶节 点的权值。设计出huffman编码的压缩算法，完成对n个节点的编码，并写出程序予以实现。 三、实验步骤及原理： 1、原理：Huffman算法的描述 (1)初始化，根据符号权重的大小按由大到小顺序对符号进行排序。 (2)把权重最小的两个符号组成一个节点， (3)重复步骤2，得到节点P2，P3，P4……，形成一棵树。 (4)从根节点开始顺着树枝到每个叶子分别写出每个符号的代码 2、实验步骤： 根据算法原理，设计程序流程，完成代码设计。 首先，用户先输入一个数n，以实现n个叶节点的Huffman 树； 之后，输入n个权值w[1]~w[n]，注意是unsigned int型数值； 然后，建立Huffman 树； 最后，完成Huffman编码。 四、实验代码：#include int min(HuffmanTree t,int i) { int j,flag; unsigned int k = MAX; for(j=1;j<=i;j++) if(t[j].parent==0&&t[j].weight 交互式多模型算法卡尔曼滤波仿真 1 模型建立 分别以加速度u=0、1、2代表三个不同的运动模型 状态方程x(k+1)=a*x(k)+b*w(k)+d*u 观察方程z(k)=c*x(k)+v(k) 其中，a=[1 dt;0 1],b=[dt^2/2;dt],d=[dt^2/2;dt],c=[1 0] 2 程序代码 由两个功能函数组成，imm_main用来实现imm 算法，move_model1用来生成仿真数据，初始化运动参数 function imm_main %交互式多模型算法主程序 %初始化有关参数 move_model %调用运动模型初始化及仿真运动状态生成函数 load movedata %调入有关参数初始值（a b d c u position velocity pmeas dt tg q r x_hat p_var） p_tran=[0.8 0.1 0.1;0.2 0.7 0.1;0.1 0.2 0.7];%转移概率 p_pri=[0.1;0.6;0.3];%模型先验概率 n=1:2:5; %提取各模型方差矩阵 k=0; %记录仿真步数 like=[0;0;0];%视然函数 x_hat_hat=zeros(2,3);%三模型运动状态重初始化矩阵 u_=zeros(3,3);%混合概率矩阵 c_=[0;0;0];%三模型概率更新系数 %数据保存有关参数初始化 phat=[];%保存位置估值 vhat=[];%保存速度估值 xhat=[0;0];%融合和运动状态 z=0;%量测偏差（一维位置） pvar=zeros(2,2);%融合后估计方差 for t=0:dt:tg; %dt为为仿真步长；tg为仿真时间长度 k=k+1;%记录仿真步数 ct=0; %三模型概率更新系数 c_max=[0 0 0];%混合概率规范系数 p_var_hat=zeros(2,6);%方差估计重初始化矩阵, %[x_hat_hat p_var_hat]=model_reinitialization(p_tran,p_pri,x_hat,p_var);%调用重初始化函数，进行混合估计，生成三个模型重初始化后的运动状态、方差 %混合概率计算 for i=1:3 u_(i,:)=p_tran(i,:)*p_pri(i); end for i=1:3 c_max=c_max+u_(i,:); end 目 录 实验一用C/C++语言实现游程编码 实验二用C/C++语言实现算术编码 实验三用C/C++语言实现LZW编码 实验四用C/C++语言实现2D-DCT变换13 实验一用C/C++语言实现游程编码 1. 实验目的 1) 通过实验进一步掌握游程编码的原理； 2) 用C/C++语言实现游程编码。 2. 实验要求 给出数字字符，能正确输出编码。 3. 实验内容 现实中有许多这样的图像，在一幅图像中具有许多颜色相同的图块。在这些图块中，许多行上都具有相同的颜色，或者在一行上有许多连续的象素都具有相同的颜色值。在这种情况下就不需要存储每一个象素的颜色值，而仅仅存储一个象素的颜色值，以及具有相同颜色的象素数目就可以，或者存储一个象素的颜色值，以及具有相同颜色值的行数。这种压缩编码称为游程编码，常用(run length encoding，RLE)表示，具有相同颜色并且是连续的象素数目称为游程长度。 为了叙述方便，假定一幅灰度图像，第n行的象素值为： 用RLE编码方法得到的代码为：0@81@38@501@40@8。代码中用黑体表示的数字是游程长度，黑体字后面的数字代表象素的颜色值。例如黑体字50代表有连续50个象素具有相同的颜色值，它的颜色值是8。 对比RLE编码前后的代码数可以发现，在编码前要用73个代码表示这一行的数据，而编码后只要用11个代码表示代表原来的73个代码，压缩前后的数据量之比约为7:1，即压缩比为7:1。这说明RLE确实是一种压缩技术，而且这种编码技术相当直观，也非常经济。RLE所能获得的压缩比有多大，这主要是取决于图像本身的特点。如果图像中具有相同颜色的图像块越大，图像块数目越少，获得的压缩比就越高。反之，压缩比就越小。 译码时按照与编码时采用的相同规则进行，还原后得到的数据与压缩前的数据完全相同。因此，RLE是无损压缩技术。 实验二图像预测编码 一、实验题目: 图像预测编码： 二、实验目的: 实现图像预测编码和解码. 三、实验内容: 给定一幅图片，对其进行预测编码，获得预测图像，绝对残差图像, 再利用预测图像和残差图像进行原图像重建并计算原图像和重建图像误差. 四、预备知识: 预测方法，图像处理概论。 五、实验原理: 根据图像中任意像素与周围邻域像素之间存在紧密关系,利用周围邻域四个像素来进行该点像素值预测,然后传输图像像素值与其预测值的差值信号，使传输的码率降低，达到压缩的目的。 六、实验步骤: (1)选取一幅预测编码图片; (2)读取图片内容像素值并存储于矩阵; (3)对图像像素进行预测编码; (4)输出预测图像和残差图像; (5)根据预测图像和残差图像重建图像; (6)计算原预测编码图像和重建图像误差. 七、思考题目: 如何采用预测编码算法实现彩色图像编码和解码. 八、实验程序代码: 预测编码程序1: 编码程序: i1=imread('lena.jpg'); if isrgb(i1) i1=rgb2gray(i1); end i1=imcrop(i1,[1 1 256 256]); i=double(i1); [m,n]=size(i); p=zeros(m,n); y=zeros(m,n); y(1:m,1)=i(1:m,1); p(1:m,1)=i(1:m,1); y(1,1:n)=i(1,1:n); p(1,1:n)=i(1,1:n); y(1:m,n)=i(1:m,n); p(1:m,n)=i(1:m,n); p(m,1:n)=i(m,1:n); y(m,1:n)=i(m,1:n); for k=2:m-1 for l=2:n-1 y(k,l)=(i(k,l-1)/2+i(k-1,l)/4+i(k-1,l-1)/8+i(k-1,l+1)/8); p(k,l)=round(i(k,l)-y(k,l)); end end p=round(p); subplot(3,2,1); imshow(i1); title('原灰度图像'); subplot(3,2,2); imshow(y,[0 256]); title('利用三个相邻块线性预测后的图像'); subplot(3,2,3)； imshow(abs(p),[0 1]); title('编码的绝对残差图像'); 解码程序 j=zeros(m,n); j(1:m,1)=y(1:m,1); j(1,1:n)=y(1,1:n); j(1:m,n)=y(1:m,n); LZ77 压缩算法实验报告 一、实验内容：使用 C++编程实现 LZ77 压缩算法的实现。 二、实验目的：用 LZ77 实现文件的压缩。 三、实验环境： 1、软件环境：Visual C++ 6.0 2、编程语言：C++ 四、实验原理： LZ77 算法在某种意义上又可以称为“滑动窗口压缩”，这是 由于该算法将一个虚拟的，可以跟随压缩进程滑动的窗口作为术语字典，要压缩的字符串如果在该窗口中出现，则输出其出现位置和长度。使用固定大小窗口进行术语匹配，而不是在所有已经编码的信息中匹配，是因为匹配算法的时间消耗往往很多，必须限制字典的大小才能保证算法的效率；随着压缩的进程滑动字典窗口，使其中总包含最近编码过的信息，是因为对大多数信息而言，要编码的字符串往往在最近的上下文中更容易找到匹配串。 五、 LZ77 算法的基本流程：1、从当前压缩位置开始，考察未编码的数据，并 试图在滑动窗口中找出最长的匹配字符串，如果找到，则进行步骤2，否则进行步骤 3。 2、输出三元符号组 ( off, len, c )。其中 off 为窗口中匹配字符串相 对窗口边界的偏移，len 为可匹配的长度，c 为下一个字符。然后将窗口向后滑动 len + 1 个字符，继续步骤 1。 3、输出三元符号组 ( 0, 0, c )。其中 c 为下一个字符。然后将窗口向 后滑动 len + 1 个字符，继续步骤 1。 代码如下： #include 《用哈夫曼编码实现文件压缩》 实验报告 课程名称《数据结构B》 实验学期 2011 至 2012 学年第一学期学生所在系部计算机系 年级 2009级专业班级计科B09—1 学生姓名韩翼学号 200907014106 任课教师盛建瓴 实验成绩 一、实验题目： 用哈夫曼编码实现文件压缩 二、实验目的： 1、了解文件的概念。 2、掌握线性链表的插入、删除等算法。 3、掌握Huffman 树的概念及构造方法。 4、掌握二叉树的存储结构及遍历算法。 5、利用Huffman 树及Huffman 编码，掌握实现文件压缩的一般原理。 三、实验设备与环境： 微型计算机、Windows 系列操作系统 、Visual C++6.0软件 四、实验内容： 根据ascii 码文件中各ascii 字符出现的频率情况创建Haffman 树，再将各字符对应的哈夫曼编码写入文件中，实现文件压缩。 五、概要设计： 本次试验采用将字符用长度尽可能短的二进制数位表示方法，即对于文件中出现的字符，无须全部都用8位的ASCLL 码进行存储，根据他们在文件中出现的频率不同，我们利用Haffman 算法使每个字符能以最短的二进制字符进行存储，以达到节省存储空间，压缩文件的目的。解决了压缩需采用的算法，程序的思路已然清晰： 1、统计需压缩文件中每个字符出现的频率。 2、将每个字符的出现频率作为叶子结点构建Haffman 树，然后将树中结点 引向其左孩子的分支标“0”，引向其右孩子的分支标“1” ； 每个字符的编码即为从根到每个叶子的路径上得到的0、1序列，这样便完成了Haffman 编码，将每个字符用最短的二进制字符表示。 3、打开需压缩的文件，再将需压缩文件中的每个ASCII 码对应的编码按bit 单位输出。 4、文件压缩结束。 六、详细设计： （1）Huffman 树简介 路径：从树中一个结点到另一个结点之间的分支构成这两个结点间的路径 路径长度：路径上的分支数 树的路径长度：从树根到每一个结点的路径长度之和 树的带权路径长度：树中所有带权结点的路径长度之和 —结点到根的路径长度 ——权值 —其中：记作：k k n k k k l w l w wpl ∑==1 《数据压缩与信源编码》实验指导书 适用专业:信息工程 课程代码: 6088619 总学时: 40 总学分: 2.5 编写单位:电气与电子信息学院 编写人:李斌 审核人: 审批人: 批准时间: 2015 年 11 月 10日 目录 实验一码书的设计和使用 (2) 实验二基于DCT变换的图像压缩技术 (8) 实验三基于小波变换的图像压缩技术 (15) 实验一 码书的设计和使用 一、实验目的 采用矢量量化算法（LBG ）获得图像压缩所需要的码书，通过码书实现图像压缩编码。 二、实验内容 对给定的一幅图像进行码书设计、编码和解码。 三、实验仪器、设备及材料 操作系统：Windowsxp ； 软件：MA TLAB 四、实验原理 要想得到好的性能编码，仅采用标量量化是不可能的。当把多个信源符号联合起来形成多维矢量，再对矢量进行标量量化时自由度将更大，同样的失真下，量化基数可进一步减少，码率可进一步压缩。这种量化叫矢量量化。 一种有效和直观的矢量量化码书设计算法——LBG 算法(也叫GLA 算法)是由Linde 、Buzo 和Gray 于1980年首先提出来的。该算法基于最佳矢量量化器设计的最佳划分和最佳码书这两个必要条件，且是Lloyd 算法在矢量空间的推广，其特点为物理概念清晰、算法理论严密及算法实现容易。 设训练矢量集为{}110,,,-=M x x x X ，待产生的码书为{}110,,,-=N y y y C ，其中{})1(10,,,-=k i i i i x x x x ，{})1(10,,,-=k j j j j y y y y ，10,10-≤≤-≤≤N j M i ，则码书设计过程就是需求把训练矢量集X 分成N 个子集)1,,1,0(-=N j S j 的一种最佳聚类方案，而子集j S 的质心矢量j y 作为码字。假设平方误差测度用来表征训练矢量i x 和码字j y 之间的失真，即： ∑-=-=1 02)(),(k l jl il j i y x y x d 则码书设计的准则可用下列数学形式表达： 最小化 ∑∑-=-==101 0),(),,(N j M i j i ij y x d w C X W f 约束条件 ∑-==101N j ij w ，10-≤≤M i 其中W 为N M ?矩阵，其元素满足： 第22卷 第12期 2006年12月 甘肃科技 Gansu Science and Technology V ol.22 N o.12Dec. 2006 文本压缩算法的比较研究 徐成俊1,舒 毅1,柴 蓉2,张其斌1,田全红1,郝 涛3 (1甘肃省计算中心,甘肃兰州730030;2西北师范大学,甘肃兰州730070;3兰州理工大学甘肃兰州730050) 摘 要:论述了4种不同的文本压缩算法。根据压缩算法的优点和缺点,在实践中,要有针对性选 择算法,用其优点,从而得到比较理想的压缩文本。关键词:压缩算法;哈夫曼;算术;L Z ;游程中图分类号:TP391 1 引言 随着计算机技术的快速发展,各种系统数据量越来越大,给信息存储特别是网络传输带来诸多的困难,己成为有效获取和使用信息的瓶颈。为了节省信息的存储空间和提高信息的传输效率,必须对大量的实际数据进行压缩。实践证明,采用数据压缩技术可以节省80%以上的费用,且一些难点问题通过压缩技术能够实现。 数据压缩技术种类繁多、应用广泛,技术不断发展,一些分支已成为当今研究的焦点。按照编码的失真程度数据压缩可以分为有损压缩和无损压缩。有损压缩即原始数据不能完全恢复,主要应用于图像和数字化的语音方面。无损压缩就是经过一个压缩后,能够产生和输入完全一致的压缩技术,主要用于存储数据库记录或处理文本文件。 2 目前主要文本压缩算法 文本压缩是根据一定方法对大量数据进行编码处理以达到信息压缩存储过程,被压缩的数据应该能够通过解码恢复到压缩以前的原状态,而不会发生信息丢失现象。发展到现在已经有很多关于文本压缩的算法,主要有Huff man 编码、算术编码等无损压缩和预测编码、量化、变换编码等有损压缩。如图1所示。 本文对常见的几种无损压缩算法进行综合分类,比较研究。 3 算法描述 3.1哈夫曼编码 美国数学家David Huff man 在上世纪五十年 代初就提出了这种编码,其主导思想是根据字符出 现的概率来构造平均长度最短的编码,并且保持编码的唯一可解性。也就是说,在源数据中出现概率越高的字符,相应码字越短;出现概率越小的字符,其码长越长,从而达到用尽可能少的码符号来表示源数据,达到压缩的效果。哈夫曼编码是一种变长的编码(因为其长度是随符号出现的概率而不同),在编码过程中,若各码字长度严格按照码字所对应符号出现概率的大小的逆序排列,则编码的平均长度是最小的。它最根本的原则是累计的(字符的统计数字3字符的编码长度)为最小,也就是权值(字符的统计数字3字符的编码长度)的和最小。 图1 文本压缩的分类 哈夫曼编码的编码过程如下:①对源信号的出现频率进行统计,每个源信号根据它出现频率大小被赋予一定的编码,高频率的信号对应短码,低频率的信号对应长码。 ②用信号对应的编码去取代源数据中的信号。在已知源数据流中各字符发生的概率情况下使用,即在压缩数据时,遵循固定的源数据符号代码表。在不允许两次扫描源文件的情况下,往往根据先验统计概率或假设构造这张代码表。压缩处理时,若源数据流中的符号与代码表中的符号相匹配,则用与之相对应的较短的代码替代该字符,否则不 实验题目：使用Haar 小波和傅里叶变换方法滤波及数据压缩 1 实验目的 （1）掌握离散数据的Haar 小波变换和傅里叶变换的定义，基本原理和方法 （2）使用C++实现数据的Haar 小波变换和离散傅里叶变换 （3）掌握数据滤波的基本原理和方法 （4）掌握使用Haar 小波变换和离散傅里叶变换应用于数据压缩的基本原理和方法，并且对两种数据压缩进行评价 2 实验步骤 2.1 算法原理 2.1.1 Haar 小波变换 （1）平均，细节及压缩原理 设{x1，x2}是一组两个元素组成的信号，定义平均与细节为(12)/2a x x =+， (12)/2d x x =-。则可以将{a ，d}作为原信号的一种表示，且信号可由{a ，d}恢复，1x a d =+，2x a d =-。 由上述可以看出，当x1，x2非常接近时，d 会很小。此时，{x1，x2}可以近似的用{a}来表示，由此实现了信号的压缩。重构的信号为{a ，a}，误差信号为 {|1|,|2|}{||,||}x a x a d d --=。因此，平均值a 可以看做是原信号的整体信息，而d 可 以看成是原信号的细节信息。用{a}近似的表示原信号，可以实现对原信号的压缩，而且丢失的细节对于最终信号的重构不会有重大影响。对于多元素的信号，可以看成是对于二元信号的一种推广。 （2）尺度函数和小波方程 在小波分析中，引入记号 [1,0)()() t X t φ=，其中， [1,0)() X t 表示区间[1，0]上的特征函 数。定义 ,()(2),0,1,...,21 j j j k t t k k φφ=-=- 称()t φ为Haar 尺度函数。由上式可知， ,()j k t φ都可以由 0,0() t φ伸缩和平移得到。 小波分析中，对于信号有不同分辨率的表示，当用较低分辨率来表示原始信号时，会丢失细节信息，需要找到一个函数来描述这种信息，该函数称之为小波函数。基本的小波函数定义如下：LZSS压缩算法实验报告
多媒体数据压缩实验报告
数据快速压缩算法的C语言实现
压缩编码算法设计与实现实验报告
交互式多模型算法卡尔曼滤波仿真
数据压缩实验指导书
数据压缩实验
LZ77 压缩算法实验报告 一
哈夫曼算法实现字符串压缩——实验报告单
《数据压缩与信源编码》实验指导书
文本压缩算法的比较研究
实验报告-数据滤波和数据压缩实验