Steps in Digital Image Processing

The steps which are used in digital image processing which are given below.

Image acquisition is the first process introduces a number of basic digital image concept that are used. The image acquisition stage involves preprocessing such as scaling.

Image enhancement is the simplest and most appealing areas of digital image processing. Enhancement simply to highlight certain features of interest in an image. It is a very subjective area of image processing.

Image restoration is an area that also deals with improving the appearance of an image. Image restoration is objective, the sense that restoration techniques tend to be based on mathematical or probabilistic model of image degradation.

Color image processing is an area that has been gaining in importance because of the significant increase in the use of digital images over the Internet. Color is used for extracting the features of interest in an image.

Wavelets are the foundation for representing images in various degree of resolution, in which images are subdivided successfully into smaller regions.

Compression deals with techniques for reducing the storage required to save image or bandwidth required to transmit.

Morphological processing deals with tools for extracting image component that is useful in the representation and description of shape.

Segmentation producers partition an image into its constituent part or objects. Segmentation is one of the most difficult tasks in digital image processing. Segmentation procedure brings the process a long way toward successful solution of imaging problems that require object to be identified individually.

Open Shortest Path First

OSPF is an interior gateway routing protocol that uses link states rather than distance vectors for path selection. OSPF propagates link-state advertisements rather than routing table updates. Because only LSAs are exchanged, rather than entire routing tables, OSPF networks converge more quickly than RIP networks.

OSPF supports MD5 and clear text neighbor authentication. Authentication should be used with all routing protocols when possible because route redistribution between OSPF and other protocols (like RIP) can potentially be used by attackers to subvert routing information.

If NAT is used, if OSPF is operating on public and private areas, and if address filtering is required, then you need to run two OSPF processes—one process for the public areas and one for the private areas.

A router that has interfaces in multiple areas is called an Area Border Router (ABR). A router that acts as a gateway to redistribute traffic between routers using OSPF and routers using other routing protocols is called an Autonomous System Boundary Router (ASBR).

A Model of the Image Restoration Process

A degradation function that, together with an additive noise term, operates on an input image f(x, y) to produce a degraded image g(x, y). Given g(x, y), some knowledge about the degradation function H, and come knowledge about the additive noise term η(x, y), the objective of restoration is to obtain an estimate f^(x, y) of the original image. We are estimating as close as possible to the original input image and, in general, the more we know about H and η, the closer f^(x ,y) will be to f(x, y). If H is a linear, positive-invariant process, then the degraded image is given in the spatial domain by    g (x, y) = h(x, y) * f(x, y) + η(x, y)

Static Route Tracking

Static Route Tracking

It is not always possible to use dynamic routing protocols on the security appliance, such as when the security appliance is in multiple context mode or transparent mode. In these cases, you must use static routes.

One of the problems with static routes is that there is no inherent mechanism for determining if the route is up or down. They remain in the routing table even if the next hop gateway goes down. They are only removed from the routing table if the associated interface on the security appliance goes down.

The static route tracking feature provides a method for tracking the availability of a static route and installing a backup route if the primary route should fail. This allows you to, for example, define a default route to an ISP gateway and a backup default route to a secondary ISP in case the primary ISP becomes unavailable.

The security appliance does this by associating a static route with a monitoring target that you define. It monitors the target using ICMP echo requests. If an echo reply is not received within a specified time period, the object is considered down and the associated route is removed from the routing table. A previously configured backup route is used in place of the removed route.

When selecting a monitoring target, you need to make sure that it can respond to ICMP echo requests. The target can be any network object that responds to ICMP echo requests. Consider choosing:

• The ISP gateway (for dual ISP support) address

• The next hop gateway address (if you are concerned about the availability of the gateway)

• A server, such as a AAA server, that the security appliance needs to communicate with

• A persistent network object on the destination network

What is WiMAX?

WiMAX actually stands for Worldwide Inter operability for Microwave Access, and is a wireless communication standard. Of the standards currently being developed for 4G it is the closest in practice to current Wi-Fi, though it provides several notable advantages. WiMAX was developed in 2001 and is described by the WiMAX forum as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL". This “last mile” refers to the often difficult process of getting access to a consumer from a local data station, be it in the form of a telephone cable, wireless device or other broadcasting technology.

WiMAX has a number of front-line uses, including at-home and mobile Internet access. Because of its large radius and relatively low cost to implement when compared to 3G or xDSL  the technology can not only compete in a local market but also be used for last-mile access in remote locations. In addition, the standard can be used as backbone for cellular technology, either by replacing current technologies or acting as an overlay in order to increase capacity. It can also be used to provide “triple-play” service, which involves the deployment of two bandwidth-intensive operations and one less bandwidth-intensive operation over a single connection. This can include, for example, high speed Internet access, Internet television and a standard phone line.

Static Routing

Multiple context mode does not support dynamic routing, so you must define static routes for any networks to which the security appliance is not directly connected.

In transparent firewall mode, for traffic that originates on the security appliance and is destined for a non-directly connected network, you need to configure either a default route or static routes so the security appliance knows out of which interface to send traffic. Traffic that originates on the security appliance might include communications to a syslog server, Websense or N2H2 server, or AAA server. If you have servers that cannot all be reached through a single default route, then you must configure static routes.

The simplest option is to configure a default route to send all traffic to an upstream router, relying on the router to route the traffic for you. However, in some cases the default gateway might not be able to reach the destination network, so you must also configure more specific static routes. For example, if the default gateway is on the outside interface, the default route cannot direct traffic to any inside networks that are not directly connected to the security appliance.

You can also use static route in conjunction with dynamic routing protocols to provide a floating static route that is used when the dynamically discovered route goes down. If you create a static route with an administrative distance greater than the administrative distance of the dynamic routing protocol, then a route to the specified destination discovered by the routing protocol takes precedence over the static route. The static route is used only if the dynamically discovered route is removed from the routing table.

Wireless Local Aea Network (WLAN)

A wireless local area network (WLAN) links two or more devices using some wireless distribution method (typically spread-spectrum or OFDM radio), and usually providing a connection through an access point to the wider Internet. This gives users the ability to move around within a local coverage area and still be connected to the network. Most modern WLANs are based on IEEE 802.11 standards, marketed under the Wi-Fi brand name.

Component of an Image Processing System.

In the 1980 and early in 1990s, the market shifted to image processing hardware in the form of single boards designed to be compatible with industry standard buses and to fit into engineering workstations cabinets and personal computers.

With reference to sensing, two elements are required to acquire digital images. The first physical device that is sensitive to the energy radiated by the object we wish to image. The second is the digitizer is a device for converting the output of physical sensing device into digital form.

Digital storage for image processing application falls into three principal categories: (1) short term storage for use during processing, (2) on-line storage for relatively fast recall and, (3) archival storage, characterized by infrequent access. Storage is measured in bytes, Kbytes, Mbytes, Gbytes, and Tbytes.

Interior Gateway Protocol (IGP)

An Interior Gateway Protocol (IGP) is a type of protocol used for exchanging routing information between gateways (commonly routers) within an Autonomous System (for example, a system of corporate local area networks). This routing information can then be used to route network-level protocols like IP.

Interior gateway protocols can be divided into two categories: distance-vector routing protocols and link-state routing protocols. Specific examples of IGP protocols include Open Shortest Path First (OSPF), Routing Information Protocol (RIP) and Intermediate System to Intermediate System (IS-IS).

By contrast, exterior gateway protocols are used to exchange routing information between Autonomous Systems and rely on IGPs to resolve routes within an AS.

Zone Routing Protocol

If a packet's destination is in the same zone as the origin, the proactive protocol using an already stored routing table is used to deliver the packet immediately.

If the route extends outside the packet's originating zone, a reactive protocol takes over to check each successive zone in the route to see whether the destination is inside that zone. This reduces the processing overhead for those routes. Once a zone is confirmed as containing the destination node, the proactive protocol, or stored route-listing table, is used to deliver the packet.

In this way packets with destinations within the same zone as the originating zone are delivered immediately using a stored routing table. Packets delivered to nodes outside the sending zone avoid the overhead of checking routing tables along the way by using the reactive protocol to check whether each zone encountered contains the destination node.

Thus ZRP reduces the control overhead for longer routes that would be necessary if using proactive routing protocols throughout the entire route, while eliminating the delays for routing within a zone that would be caused by the route-discovery processes of reactive routing protocols.

Classification of Routing Protocols

Enhanced Interior Gateway Routing Protocol

Enhanced Interior Gateway Routing Protocol (EIGRP) is an interior gateway protocol suited for many different topologies and media. In a well designed network, EIGRP

scales well and provides extremely quick convergence times with minimal network traffic.

Some of the many advantages of EIGRP are:

very low usage of network resources during normal operation; only hello packets are transmitted on a stable network when a change occurs, only routing table changes are propagated, not the entire routing table; this reduces the load the routing protocol itself places on the network rapid convergence times for changes in the network topology.

EIGRP is an enhanced distance vector protocol, relying on the Diffused Update Algorithm (DUAL) to calculate the shortest path to a destination within a network.

Major Revisions of the Protocol:

Explanations in this paper may not apply to that earlier version. We highly recommend using the later version of EIGRP, as it includes many performance and stability enhancements.

Integrated or Dual IS-IS (Intermediate System-to-Intermediate System)

The IS-IS Routing Protocol may be used as an IGP to support IP as well as OSI. This allows a single routing protocol to be used to support pure IP environments, pure OSI environments, and dual environments. Integrated IS-IS is deployed extensively in an IP-only environment in the top-tier Internet service provider (ISP) networks. The IS-IS working group of the Internet Engineering Task Force (IETF) developed the specification for Integrated IS-IS (RFC 1195).

Two primary methods are available for routing protocols to support dual OSI and IP routers. One method, known as "Ships in the Night," makes use of completely independent routing protocols for each of the two protocol suites. This specification presents an alternative approach, which makes use of a single integrated protocol for interior routing (that is, for calculating routes within a routing domain) for both protocol suites.

By supporting both IP and OSI traffic, this integrated protocol design supports traffic to IP hosts, OSI end systems, and dual end systems. The IS-IS Protocol can be used to support pure-IP environments, pure-OSI environments, and dual environments. IS-IS allows the interconnection of dual (IP and OSI) routing domains with other dual domains, with IP-only domains, and with OSI-only domains.

The Origins of Digital Image Processing & Application areas in Digital Image Processing Medical Images

 One of the first application of digital image was in the newspaper industry, when picture were first sent by submarine cable between London and New York. Digital image processing techniques began in the late 1960s and early 1970s which is to be used in remote Earth resource observations and astronomy and in medical imaging. Computerized tomography (CT) is one of the most important events of image processing in medical diagnosis. Computerized axial tomography is a process in which a ring of detectors encircles a patient and an X-Ray source, concentric with detector ring, rotates about the patient.