Image Segmentation: Theories and Technology

Image Segmentation: Theories and Technology Theoretical Concepts and Technical Aspects on Image Segmentation Image segmentation is a very significant area in computer vision. Image segmentation, partitions an image into multiple regions based on certain similarity constraints. This acts as the pre-processing stage in several image analysis problems like image compression, image recognition etc. Segmentation is the vital part for the successful extraction of image features and classification. Image segmentation can be defined as the partition of an image into several regions or categories. These regions can be similar in any features like color, texture, intensity etc. Every pixel in an image is assigned to any one of the categorised region. Quality of segmentation is described as pixels in the same region are similar in some characteristics whereas pixels in different regions differ in the characteristics. The segmentation process includes restoration, enhancement, and representation of the image data in the required form. Image Segmentation Techniques Image segmentation techniques can be broadly classified based on certain characteristics. Basic classifications of image segmentation techniques include local and global image segmentation techniques. The segmentation method that is concerned with segmenting specific parts or region of image is known as local image segmentation. The segmentation method that is concerned with segmenting the whole image, consisting of very large number of pixels is known as global image segmentation. The next category of image segmentation method is based on the properties of the images to be segmented. It is categorised as discontinuity detection based approach and similarity detection based approach. In discontinuity detection based approach, the segmentation is based on discontinuities in the images like edge based segmentation and similarity detection based approach is based on similarity of regions like Threshold based, Region growing, Region Splitting and Merging etc. The segmentation technique which is based on the information of the structure of required portion of the image is known as structural segmentation. Most of the segmentation methods are stochastic type, where the segmentation is completely depended upon the discrete pixel values of the image. Threshold based segmentation method is the simplest method of segmentation. The image pixels are segmented based on the intensity level. This kind of segmentation is more applicable for images where the objects are lighter than the background. This method is based on prior knowledge of the image features. There are mainly three types of threshold based segmentation. Global Thresholding: This method is done using a proper threshold value. The threshold value will be constant for the whole image. Output of the image is based on this threshold value. Variable Thresholding: In this type of segmentation method the value of threshold can vary in a single image. Multiple Thresholding: In this kind of thresholding, the output of segmentation is based on multiple threshold values. Threshold values can be computed from image histograms. In [1], threshold based level set approach based on threshold based segmentation and fast marching method [2] for medical image segmentation is proposed. To im prove the image acquisition process in computer vision, threshold based segmentation method based on entropy criteria and genetic algorithm is mentioned in [3]. Edge based segmentation method is based on the sudden change of intensity values in an image. In image processing, object boundaries are represented using edge. Edge based segmentation works by identifying the region of abrupt intensity change in an image [4]. Mainly there are two types of edge based segmentation methods. Grey Histogram Technique: In this method the foreground is separated from the background based on a threshold value. Choosing the correct threshold value creates a problem. Gradient Based Method: Gradient can be defined as the first derivate of the image near the edge. Higher change in the intensity values between two regions is depicted by the high value of gradient magnitude. In order to perform multi scale image segmentation an edge based auto threshold generating method is introduced in [5]. Another method for edge detection using variance filter is introduced in [6]. Theory based segmentation method uses derivatives from several fields. Several types of this kind of algorithm includes, Clustering based segmentation: In this method clusters are formed based on the similarity criteria (size, color, texture etc). Methods include k-means clustering, fuzzy clustering, hard clustering etc [7]. Artificial Neural Network: In this method the neuron represents the pixels and segmentation is performed with the help of trained images. Methods using Wavelet Decomposition and Self Organization Map of artificial neural networks are proposed [8]. Region based segmentation [13] methods are similar to edge based segmentation. The advantage of region based segmentation upon edge based is that, the former is more immune to noise. In this method, the region of an image is either splitted or merged into areas based on similarity. Region Growing: the collection of pixels is grouped into a region with similar properties [9]. Region Splitting and Merging: Here the image is further subdivided into several regions based on some pre-defined criteria. Graph cut image segmentation is a very significant technique of segmentation under region based segmentation. Several techniques of region growing methods include techniques that combine edge and region based information using morphological watershed algorithms [10]. In this method, initially a noise filter along with magnitude gradient is used and pre segmentation is performed through region merging. A region similarity graph is then produced and final segmentation is performed using Multi Class Normalized Cut. This technique overpowers the Spectral clustering method. As the method mentioned is a time consuming task, new method is presented [11]. For the purpose of detecting objects sharply, least square method is used for region based segmentation. Here the local information is also considered by calculating the weight matrix. This segmentation technique is optimum and fast. Graph-cut Image Segmentation As mentioned in the above methods, the techniques either use the region information or use the boundary information [12]. This results in limited segmentation. In graph cut segmentation optimal result for energy function is computed and segmentation is based on that result. Basics of Graph-Cut An undirected graph, set of vertices and a set of edges, are considered. Vertex represents the pixels in an image and edges denote the connection between the adjacent pixels. There exists a source and sink node which holds the foreground and background respectively. In graph cut method, each edge is assigned with a non-negative weight which coins the term cost. [12] A graph cut is actually the partitioning of the edge set into several component sets. Graph cut method can be either min cut or max cut. Min cut can be defined as cut through minimum cost and max cut can be defined as the cut through maximum cost. That is after the cut performed, the vertices are divided into two sets, source and sink, which holds the foreground and background pixels respectively. Implementing graph cut method assigns value 1 to the pixels in the foreground and 0 to the pixels in the background. This is achieved through minimum graph cut method by minimizing the energy function. Types of Graph Cut Based Algorithm The graph cut based segmentation can be mainly divided into three types. They are Speed-up based graph cut, Interactive based graph cut and Shape prior based graph cut. The speed up based graph cut method is used to improve the speed of the graph cut method through parallel computing. Earlier implementation was based on CUDA code [14]. The best way to speed up the computational time is to reduce the number of graph nodes while reconstructing the graph [15] [16]. Another method used for speed up based graph cut method is clustering based graph cut. Clustering based graph cut is based on reducing the number of nodes by grouping similar pixels into a single cluster and treating a cluster as a node. Watershed based method is another important speed up based approach where, gradient images are considered and the concept of catchment basins are used [15]. Interactive based graph cut plays a very important role in segmentation of natural images and the situations where the segmentation requires high precision. In this kind of methods the seed points are selected and then segmentation is performed based on these points. Several methods are performed using the concept of bounding box, where the centre portion of the bounding box corresponds to the object and histogram is constructed. The area outside the bounding box is considered as the background region [17] [18]. Certain interactive segmentation is performed by choosing both the foreground and background region together. Iterative interactive graph cut segmentation is also performed. Shape prior based graph cut segmentation finds its importance where the image to be segmented is affected by noise, diffuse edge, obstructed objects etc. In this kind of segmentation, the shape information is included as the energy function [19] [20]. Case Study In this chapter a graph based image segmentation method is explained. The efficient graph based image segmentation method initially considers the input image as a graph. The pixel values are considered as the nodes of the graph and edge is drawn between the adjacent pixels. The edge weight is represented by the difference between adjacent pixels. Initially, the considered edge set is sorted in the increasing order of edge weight. The segmentation process actually segments the entire vertices set into disjoint sets based on some similarity function. The vertex set is initially randomly partitioned into several component sets. This is considered as the initial segmentation. The vertices producing the largest edge weight is considered first. Let the two vertices be v1 and v2. Then check whether these two vertices belong to disjoint component sets in the previous segmentation (initial segmentation). If the two vertices are in disjoint component sets then compare the edge weight connecting these vertices to the internal difference of these two component sets. If the weight of the edge connecting these vertices is smaller when compared to the internal difference, then these two components are merged. Otherwise, it is neglected. On continuing these steps till the smallest edge weight, a final segmentation of the input image is obtained. Expected Outcome In the proposed chapter, an exhaustive review on image segmentation such as threshold based, edge based, graph based and region based segmentation will be included. The various approaches employed for graph cut segmentation include interactive graph cut, efficient graph cut, shape based graph cut and speed up based graph cut. The chapter would conclude with results on a list of benchmark images. At the enclosure of the chapter, open research problems will be discussed.

Response To Beijing Games Book

The field of sports has definitely gained an unquestionable significance and obvious implications among people and within societies. Such relevant characteristics concerning the sports discipline have resulted in making it as an important topic to be presented in a literary work. This is because facts and stories about sports are essential to be discussed in order for its underlying principles and messages to be learned and ultimately realized by the public.Sports field in today’s contemporary setting has achieved an apparent prominence. The said fame is attributed to the success of the quintessential sports event – the Olympics.The advent and emergence of the Olympics have paved the way for recognition of various kinds of sports, their respective players or athletes and most importantly, the acknowledgement of the host countries where the said sports occasion is held every four years. The purpose, essence and valuable effects of Olympics to its host nation were what Su san Brownell (2008) effectively and successfully exemplified in her book â€Å"Beijing Games: What the Olympics Mean to China. † The Brownell material provided the public with clear insight about the meaning and effects of the 2008 summer Olympics to China.In the book, the author attained her goals and the narrative’s worth when they efficiently imparted to the readers the importance of hosting the Olympic Games to the country of China. In doing so, the â€Å"Beijing Games† book revealed that the meaning of Olympics to China lies on the reality that Olympics as Western civilization component can, in fact, possibly occur and affect the Far East culture. The attempt of Brownell and her book to emphasize the triumphant connection that transpired between Olympics and China led to the recognition of the beneficial impact of Olympic Games to China as well as the nation’s worldwide influence.The book therefore served as a very inspiring and awakening literary wo rk where the effect and how Olympics change its host country as well as how China impacted and altered the Olympic were eventually realized. Written by Brownell months before the 2008 summer Olympic Games in Beijing, the book â€Å"Beijing Games† is evidently topical to China in showing the nation as one of the powerful and influential countries in Asia or the Far East part of the world.In general, the work acted as defender of the history and sports background of China as well as its political structure. This was carried out by the book with its specific criticism against the Western culture’s manner of interpreting and performing the Olympics (Brownell, 2008). â€Å"Beijing Games’ was not purely sports-oriented as several historical, political and social facts and events relating to China were discussed such as the 1989 Tiananmen Square tragic incident.Hence, in organizing the book, the author made seven chapters that talked about a number of issues. These in clude the disparities between the respective historical encounters with Olympic sports or the physical endeavors of China and the rest of Western countries (Brownell, 2008). The book also presented how Chinese regarded their affiliation with the International Olympic Committee or IOC, the coverage made by Western media concerning China as a nation and its sports.Foremost these topics, the Brownell book is to be significantly noted by its intriguing yet powerful presentation on whether Beijing is destined to change the Olympic’s history and nature or vice versa (Brownell, 2008). In order to understand and appreciate better the Beijing Games book, it is empirically essential to analyze how the material appeared and considered by the readers. Additionally, it is valuable to react to the book by discussing both its main and weak points. In responding to the book, the general concepts which pertain to China and the Olympics are first to be evaluated.On the whole, the book is to be commended for its efforts at disclosing the ability of the Far East civilization to hold a global sports event such as the Olympics thereby making people realize that the quintessential sports activity should not be made exclusive to Western countries. Since China embarked on what seemed like a remarkable sports undertaking, the book asserted that it is but just practical to praise and commend the country for its firm principle and practice of bringing Olympics to the other side of the world.Due to its emphasis on the capability of China, the book is to be equally acclaimed because the author has successfully disputed a misleading and incorrect notion about the sports history and background in China. The book then did well in making the world recognize that Beijing aspiration to host the 2008 summer Olympics is attributed to an enormous desire to overcome a lasting wrong impression about China’s inability towards sports or little or none at all connection with the said field .In asserting China’s power and influence in sports, the book’s notable criticism against the Western control of what is projected to be a global sports activity has worked to the advantage of China and the field of sports in general. This is because through the book, the international public was provided with the fact that the country has, in fact, rich and original sports background or nature.Based from the efforts of the author or the book, various political and social concerns that prevented sports from flourishing in China were presented, all aimed at ending the many forms of discriminations and misrepresentation on the function of Olympics sports in China and the apparent neglect done by Western cultures. Personally, I considered the book to be generally acceptable and commendable. While its organizational presentation appeared to be loosening, its principles and objectives made â€Å"Beijing Games† as one literary material worth reading and referred to ot her sectors of the public aside from sports.This is because the book is supposed to impart important messages or lessons to anyone. That is, the field of sports is a universal discipline which needs to be equally adhered to and uphold by worldwide audience. The realization of the meaning of Olympics to China showed how the book ultimately achieved its very essence and goals. Reference Brownell, S (2008). Beijing Games: What the Olympics Mean to China. New York: Rowman & Littlefield

Should Richard M. Nixon visit Red China?

That is an interesting question to which one could offer many good reasons to both sides of the argument. However, to fully examine the decision made, one would have to look at many of the background information surrounding the voyage. This includes; Nixon's popularity with America as well as the Vietnam War, which at that time had yet to be resolved, America's relationship with the Soviet Union, America's relationship with Taiwan and the Republic of China, the relationship between the People's Republic of China and the Republic of China, America's past relations with China as well as their distrust on Communism, and China's relationship with the world. After studying each of these, one can form a decision of whether Nixon should or should not go to Red China. Richard Nixon was an extremely unpopular president. This was primarily due to the war in Vietnam that he didn't even get America into. However, while he was not the one who got America into Vietnam he had the important job of getting America out, a task, which would take him four years, four years of discontent in America. Nixon had decided to invade Cambodia, which had been completely off-limits, however the Communist troops had been using it as a rest area and supply base1. While the invasion itself was a successful operation it caused havoc back in the United States. As demonstrated when 100,000 protesters showed up in Washington D. C. to demonstrate their anger with the decision of invasion2. Nixon's policy of â€Å"Vietnamization†3, which included training Vietnamese soldiers to replace American soldiers, worked well and by 1971 has sent many American troops back to the United States. At the same time Nixon also had his right-hand man Henry Kissinger in secret discussion with North Vietnamese forces, discussing peace negotiations. America and North Vietnam reached a ceasefire agreement on January 27, 1973, which officially withdrew Americans from Vietnam and allowed them to achieve â€Å"peace with honor†4. The war itself however, did not end until April 29, 1975. This war had a large effect on Nixon's decision to visit Red China as China had been supporting the Communist North Vietnam forces throughout the war, while America had been in Vietnams fighting against them, supporting the Southern side. This created another time for Americans to show their dislike and distrust of Communism. However, China was a powerful country and if America could make good relations with them it would help to keep negotiations strong between the North Vietnam and America. Therefore, the war in Vietnam was an important thing to consider when deciding whether Nixon should visit the Communist, Red China. America had not always had a very strong relationship with the Soviet Union. Two of the world superpowers had been at constant fear of attack by each other during the Cold War. This Cold War came about for many reasons, two being, Truman's desire to stop the spread of communism5, and the atomic weapons that each country had. However, the most important factor that created this Cold War was fear. Each country had large, irrational fears of the other, the Americans feared another dictator trying to take over the world, and the Soviets feared a powerful invader6. The Americans had a monopoly on the atomic weapons, and weren't sharing their secrets; this alarmed the Soviets and prompted them to make atomic weapons of their own. Each country was unsure of what the other had, thus creating the constant suspicion. Also feeding this fear was propaganda that each country used. In America politicians were constantly telling the American public about the terrors of Communists and how everyone was in danger because of the evil Soviet Communists planning an attack7. The Cold War was an important thing for Nixon to consider because it was still going on and America had been expressing hated toward Communists since the beginning. Visiting China would be good though because it could speed up the end of the Cold war that they were stuck in. Also recognizing a Communist country that was so close to the Soviet Union would be handy for intelligence purposes, as they would be closer to the enemy and could get a better idea of what was going on, it could also make the war less between Communism and America and focused on the Soviet Union and America. The relationship between the United States and the Soviet Union eventually did ease up slightly. This started in 1952 when Nikita Kruschev paid a visit to America with talks of â€Å"peaceful coexistence† between the two countries8. At the time that he did this he had begun to see his ally China as more of an enemy than America was9. Also at the time the Soviets had, had recent victory over the Americans with the success of the Sputnik satellite, two years prior to the visit. This visit did not create any drastic change or movements towards peace between the two countries, however it was one good step in the direction towards â€Å"peaceful coexistence†. This meeting would be a good reason for Nixon to go to China as it shows that two countries that believe and practice completely different forms of government can still meet and recognize one another. He would want to take pointers from this meeting of good things that Kruschev did while visiting America and expand upon those so that his meeting in China would not only be successful but productive as well, something that Kruschev's visit was not. During the Cultural Revolution American aided the Nationalist, Republic of China, by giving them nearly 1 billion dollars worth of weapons and other necessities10. America pressured the Nationalist party, led by Chiang to accept some of Stalin's demands, such as the use of northern ports to expand the Russian economy. By them meeting these demands they were given full Soviet support, and were recognized by both America and the Soviet Union as the only China11. Having Americans helping the Nationalists very much upset the Communist party, and they ceased peace talks. Then Chaing's army completely disregarded some advice given by General Marshall, whom was later made the Secretary of State. When Marshall became the secretary of state he would not allow America to further heavily involve itself with the Cultural Revolution. The Korean War was the first time that American and Communist forces had the opportunity to compete. American forces were helping South Korea from the invading, communist North Korean troops. China had never intended on entering into the war, however when American forces continued to get too close to their border in the intent of taking over North Korea, instead of just helping South Korea in keeping their territory. China had sent out warnings to them, not to get close and so when America got too close, Chou En-lai, the Chinese premier sent out masses of troops, which easily surrounded American and South Korean troops12. Nixon would have wanted to consider this event before going to China because it was another event in which the Americans were fighting against Communism as well as the Chinese. However, it would be good to go to China because then Nixon would be able to show the world that America was not a sore loser, that despite being brutally attacked by the Chinese they were still able to make relations and work towards peace and prosperity together. The People's Republic of China and the Republic of China had a very poor relationship ever since their split after the Cultural Revolution. The ROC got Taiwan as their mainland as well as two small islands, Quemoy and Matsu13. These two islands were very close to the mainland of PRC's China, which was a fact that had always irked Mao. Mao tried to take the islands by force with his military, however unfortunately he was unsuccessful as the ROC had America to support them and Mao had no one as the Soviet Union had not come in time. This was a small event, yet it would be another thing for Nixon to look at. It would be a good thing for America to recognize Red China, as it would be a form of apology for fighting against them previously with their enemy the ROC. It would show that America has realized which China is the true China, which is something that would please Mao and would make him more likely to be open to trade with America. After the Cultural Revolution in China the issue of their seat in the United Nations Security Council arose. After World War two the UN was created and five of the powerful, victorious countries were placed into permanent seats on the Security Council. These were the Soviet Union, France, Great Britain, the United States, and China. When China split the People's Republic felt that they should replace the Republic of China on the Security Council as they now represented China. This did not go over well with the United States, who did not want more Communist countries on the council, also the United States were allies of the Nationalist China. An early solution was dual representation, however Mao refused to sit next to another China, as this gives the idea that there were two Chinas, when he was so adamant that his China was the only one. 14 Albania then proposed to admit the People's Republic of China into the UN, and they were successful in getting the votes. This got Taiwan out of the Security Council and the People's Republic in15. The Americans were unhappy about the results, as they had lost face when everyone voted against Nixon's proposal of dual representation. It would be a good thing for Nixon to go to China and recognize them because it would show that they were still a strong country and that they were ready to move past this one incident. By moving past it they would be able to work together and agree on things, which would be good for both of them to have allies as the more allies a country has the more powerful they become. Americans, had for a long time completely distrusted all things Communist. The American government used propaganda often to portray to the American public how scary and evil Communists are. They were mostly stories that they built off of the Soviet totalitarian system16. They did this propaganda through books, pamphlets, comics, films, and radio throughout the entire Cold War. The American people were forced to believe that China was a part of this world wide Communist conspiracy to overthrow American power and destroy Western Democracy. Movies were a popular way of propaganda, as it could show with full images how bad the Communists were such as â€Å"Red Nightmare: The Commies are Coming†. Movies, such as that one show Communists coming to America and just destroying everything that made America run. Not all the movies made to demonstrate the evil of Communists had to be just about them, in the James Bond movies filmed throughout the Cold War feature Russians as the bad guy and Bond coming to save the day18, this movie was not about Communism, it just found a very subtle way to further demonstrate that Communists are bad. Since all the propaganda was fed by the government, Nixon visiting China, a Communist country would be a good first step into changing the views of the American people towards Communists. While America would not need to switch and become a pro-Communism country they could start to settle the dispute against Communist countries. If America could make alliances with a powerful Communist country that could make other Communist countries like them. The United States and the Republic of China had, had amicable past relations. America had traded with the Republic of China, mostly weapons for years and continued to do so after their split from the Mainland China. The United States really helped Taiwan get started shortly after it formed it's own China. They did this through enforcing it's military so that in the event of an attack by the People's Republic of China, they would be well protected. They also traded with them so that their economy could get going and perhaps gain them some relationships with other countries in the world. This relationship between Taiwan and the United States is something that Nixon would have wanted to consider before going over to the People's Republic of China. This is because Mao was still completely refusing to speak the Republic of China, because he hated the idea of Two Chinas. In Taiwan they refused to talk to he People's Republic until they were no longer a Communist country. By going to Red China Nixon would not necessarily be apologizing to Mao and Chou En-lai about what happened in the past, but would rather be moving on and working towards an alliance, with which they can help each other in becoming even more powerful. In conclusion, America should recognize the People's Republic of China. The decision would have taken a lot of consideration but all the good things that would come out of the decision would heavily out-weigh anything negative. Visiting Red China would be a big step in the right direction and would help out the United States in many ways. So despite the American hated for all things Communist an official visit to Communist China would be a very good thing to do.

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