Monday, August 5, 2013

acu pressure

How to apply acupressure


What is acupressure?

Acupressure (sometimes written as "accupressure") is a technique related to acupuncture, where the energies of the body are regulated by manipulating points on the body. This has effects on the emotions, tension and physical conditions.
The points are commonly called "acupuncture points," "pressure points," "acupoints" or "acupressure points."

Acupressure techniques: Pressing and reducing points

There are two ways that acupressure points are manipulated: pressing (reinforcing) and reducing them. Most are probably familiar with the first, but not with the second method.
pressing an acupressure point (SI-5)To press points, use something blunt. Usually the fingers are used to press, but I find that for many points the fingers may be a bit too thick, so you'd have to press quite long and firmly. Ideal would be something 3 to 4 mm thick, like a (preferably used) pencil eraser that's on the other side of a pencil. Some points can be pressed using a fingernail.
Pressing points for less than half a second can already have a distinguishable effect. So for just trying out a point you could press it only briefly. To get a full effect however, pressure should be applied for at least half a minute, but preferably longer. One to two minutes should do.
To reduce a point, turn a finger over it in counter-clockwise direction, also for one to two minutes. (What happens when you do this is explained in "What manipulation of points brings about.") Clicking on the picture of points that need to be reduced displays a video showing how this is performed (clicking again stops the video).
I think it's a good idea not to get into the habit of doing the same points every day. Do them when you feel you need them, don't overdo it. Pay attention to what effects points have on you.
If you're weakened (from age, disease or whatever), be sure to not reduce points more often then necessary. You could also additionally press these points for a few seconds.
Do a point on both sides of the body.

Feeling if it works

When you are not feeling any effects from pressing points, several things may be the case.
You may not be pressing on the exact right spot (acupuncture points are about 0.5 mm diameter, so you'll have to be precise). Try different spots around the location you first tried.
You shouldn't press lightly, but you shouldn't hurt yourself either. Also, don't press for just a few seconds (although if you're very sensitive you might already notice effects then).
To feel if acupressure is working (for knowing that the location of the point is accurate), I usually sense what's happening in my face. Almost all points in the list on this site have some effect here. Many of the points also have some subtle effect on the quality of vision. You may see more clearly and more colors. Meditation will develop your ability to feel the effects.
If you're using a point quite often, or if you don't need a point, the effect may become very little or unnoticeable.
If you're tense, you may not feel much, although usually you'll become less tense by using the techniques on this site.

Using information from other sources ("cun")

To be able to use information from other sources for locating points, you'll need to know what the "cun" is.
1 cun = 1 thumb widthThe "cun" is the standard unit of measurement for the body used in acupuncture. As everyone's body has different dimensions, it is defined according to the person whose body is to be treated.
1 cun = width of the thumb, in the middle, at the crease
3 cun = combined breadth of the 4 fingers, at the level of the pinky finger's first joint above the palm of the hand
12 cun = the distance from the elbow crease to the wrist crease.

What manipulation of points brings about

Acupuncture points can be manipulated in various ways. To keep things simple, acupressure books usually just mention pressing the points.
If you've ever seen an acupuncturist you may have noticed that he will turn needles after inserting them or do other manipulations. Acupuncturists also apply heat by burning stuff called "moxa" or using a laser, or apply electric currents.
By simply pressing a point, you are reinforcing it. You, thereby, increase energy in areas that the point influences. Reducing a point is actually not the opposite of reinforcing it. By reducing, you remove a blockage of energy. A blockage may be felt as tension, pain or heat. Energy accumulates there, which starts moving again after removing the blockage. So if you reduce a point after you reinforced it, you get reinforcement and removal of energy blockage. They don't cancel each other out.
In acupressure, you can reduce a point by continually moving a finger counterclockwise over it. An acupuncturist will turn his needle immediately after insertion.
It's also possible to apply heat to a point to warm it. This is an advanced technique that may injure your energy system, so it's best to stay away from this.

Why you shouldn't use needles

As for using needles, I've tried that, but have been discouraged to continue using them by both an acupuncturist and a healer. The acupuncturist thought it was dangerous because you can damage tissue, and difficult as you can't access points that well yourself. You may damage blood vessels, nerves, tendons or bone, which can all be quite painful. On the breast or shoulders, you may puncture the lung.
On an energetic level, the fear that comes with using needles on yourself may damage the First Chakra. This may worsen your problems.
Using needles as an amateur may not even be legal.
I found that I feel more clearly what's happening in my body from acupressure than from acupuncture, whether administered by a licensed acupuncturist or by myself.

Using little balls and tape

I devised a safe and effective way to press acupuncture points for an extended period of time. I use adhesive tape for use on skin to press ball-bearing balls on points. It doesn't work with all points (e.g. it does not work well for ST-36, the point beneath the knees) but for many it's quite good.
point LU-9 pressed using ball and tapeThe metal balls I use are 4 mm diameter and I apply nylon rings (also bought at a hardware store) on top of them to supply a larger surface to the tape. The inside diameter of the nylon rings should be 3 mm. Perhaps you could also use the more common metal rings, but for some indefinite reason I prefer the nylon variety. The rings avoid bulging and thus press the ball a bit deeper into the skin.
Keeping the balls in place for 5 - 30 minutes should do.
A similar method is sometimes used for ear acupuncture. Little seeds are then taped to the ear.

How to apply acupressure


What is acupressure?

Acupressure (sometimes written as "accupressure") is a technique related to acupuncture, where the energies of the body are regulated by manipulating points on the body. This has effects on the emotions, tension and physical conditions.
The points are commonly called "acupuncture points," "pressure points," "acupoints" or "acupressure points."

Acupressure techniques: Pressing and reducing points

There are two ways that acupressure points are manipulated: pressing (reinforcing) and reducing them. Most are probably familiar with the first, but not with the second method.
pressing an acupressure point (SI-5)To press points, use something blunt. Usually the fingers are used to press, but I find that for many points the fingers may be a bit too thick, so you'd have to press quite long and firmly. Ideal would be something 3 to 4 mm thick, like a (preferably used) pencil eraser that's on the other side of a pencil. Some points can be pressed using a fingernail.
Pressing points for less than half a second can already have a distinguishable effect. So for just trying out a point you could press it only briefly. To get a full effect however, pressure should be applied for at least half a minute, but preferably longer. One to two minutes should do.
To reduce a point, turn a finger over it in counter-clockwise direction, also for one to two minutes. (What happens when you do this is explained in "What manipulation of points brings about.") Clicking on the picture of points that need to be reduced displays a video showing how this is performed (clicking again stops the video).
I think it's a good idea not to get into the habit of doing the same points every day. Do them when you feel you need them, don't overdo it. Pay attention to what effects points have on you.
If you're weakened (from age, disease or whatever), be sure to not reduce points more often then necessary. You could also additionally press these points for a few seconds.
Do a point on both sides of the body.

Feeling if it works

When you are not feeling any effects from pressing points, several things may be the case.
You may not be pressing on the exact right spot (acupuncture points are about 0.5 mm diameter, so you'll have to be precise). Try different spots around the location you first tried.
You shouldn't press lightly, but you shouldn't hurt yourself either. Also, don't press for just a few seconds (although if you're very sensitive you might already notice effects then).
To feel if acupressure is working (for knowing that the location of the point is accurate), I usually sense what's happening in my face. Almost all points in the list on this site have some effect here. Many of the points also have some subtle effect on the quality of vision. You may see more clearly and more colors. Meditation will develop your ability to feel the effects.
If you're using a point quite often, or if you don't need a point, the effect may become very little or unnoticeable.
If you're tense, you may not feel much, although usually you'll become less tense by using the techniques on this site.

Using information from other sources ("cun")

To be able to use information from other sources for locating points, you'll need to know what the "cun" is.
1 cun = 1 thumb widthThe "cun" is the standard unit of measurement for the body used in acupuncture. As everyone's body has different dimensions, it is defined according to the person whose body is to be treated.
1 cun = width of the thumb, in the middle, at the crease
3 cun = combined breadth of the 4 fingers, at the level of the pinky finger's first joint above the palm of the hand
12 cun = the distance from the elbow crease to the wrist crease.

What manipulation of points brings about

Acupuncture points can be manipulated in various ways. To keep things simple, acupressure books usually just mention pressing the points.
If you've ever seen an acupuncturist you may have noticed that he will turn needles after inserting them or do other manipulations. Acupuncturists also apply heat by burning stuff called "moxa" or using a laser, or apply electric currents.
By simply pressing a point, you are reinforcing it. You, thereby, increase energy in areas that the point influences. Reducing a point is actually not the opposite of reinforcing it. By reducing, you remove a blockage of energy. A blockage may be felt as tension, pain or heat. Energy accumulates there, which starts moving again after removing the blockage. So if you reduce a point after you reinforced it, you get reinforcement and removal of energy blockage. They don't cancel each other out.
In acupressure, you can reduce a point by continually moving a finger counterclockwise over it. An acupuncturist will turn his needle immediately after insertion.
It's also possible to apply heat to a point to warm it. This is an advanced technique that may injure your energy system, so it's best to stay away from this.

Why you shouldn't use needles

As for using needles, I've tried that, but have been discouraged to continue using them by both an acupuncturist and a healer. The acupuncturist thought it was dangerous because you can damage tissue, and difficult as you can't access points that well yourself. You may damage blood vessels, nerves, tendons or bone, which can all be quite painful. On the breast or shoulders, you may puncture the lung.
On an energetic level, the fear that comes with using needles on yourself may damage the First Chakra. This may worsen your problems.
Using needles as an amateur may not even be legal.
I found that I feel more clearly what's happening in my body from acupressure than from acupuncture, whether administered by a licensed acupuncturist or by myself.

Using little balls and tape

I devised a safe and effective way to press acupuncture points for an extended period of time. I use adhesive tape for use on skin to press ball-bearing balls on points. It doesn't work with all points (e.g. it does not work well for ST-36, the point beneath the knees) but for many it's quite good.
point LU-9 pressed using ball and tapeThe metal balls I use are 4 mm diameter and I apply nylon rings (also bought at a hardware store) on top of them to supply a larger surface to the tape. The inside diameter of the nylon rings should be 3 mm. Perhaps you could also use the more common metal rings, but for some indefinite reason I prefer the nylon variety. The rings avoid bulging and thus press the ball a bit deeper into the skin.
Keeping the balls in place for 5 - 30 minutes should do.
A similar method is sometimes used for ear acupuncture. Little seeds are then taped to the ear.

Thursday, February 7, 2013

vector quantization

Introduction




        Vector quantization (VQ) has been commonly used in the compression of image and speech signals. In vector quantization, a reproduction vector (codevector) in a predesigned set of vectors (codebook) approximates each set (vector) of the input signal. This representative codevector, the nearest neighbor of the source vector, gives the least dissimilarity (distortion) among all the codevectors in the codebook. In vector quantization, compression is achieved by transmitting or storing the indices associated to the codevectors instead of the codevectors because of the far fewer bits required for the indices. The following Figure 1 shows the principle of the resulting encoder and decoder.


          Figure 1: The principle of the encoder and the decoder used in vector quantization. Source [27]



        Vector quantization is the extension of scalar quantization. Basically in signal processing converting a analog source - continuous time and amplitude- into a digital source - discrete time and amplitude - results in two operations: sampling and quantization. In the following context, a source is regarded as stochastic process described by a probability density function. A particularly realization of such a source is a signal. So sampling means to convert a continuous-time signal into a discrete-time signal –a set of data samples. Quantization means to convert a continuous-amplitude signal into a discrete-amplitude signal.

        Vector quantization is characterized by its dimension, equal to the number of data samples in a set, which is quantized jointly as a single vector. Then vector quantization means to approximate an infinite set of vectors by a limited set of vectors. This approximation can be regarded as a lossy compression method characterized by its distortionand its compression rate. The distortion measures the loss of information induced by the quantization. For images is this loss a degradation in details. The compression rate measures the gain in representing the samples by passing from an infinite set to a limited set. In the sense of transmission, a large compression rate implies a low bit rate and low compression rate implies a large bit rate to transmit the same number of data samples in the same time.

        In image processing vector quantization is used as a lossy compression method to reduce psychovisual as well as statistical redundancies in the image data. begin chapter|next chapter
    1.1 Principles of Vector Quantization
        Vector quantization is based on two principal theories: Shannon rate distortion theory and high-resolution theory. The two theories are complementary in the sense that Shannon rate distortion theory prescribes the best possible performance of quantization with a given bit rate and asymptotically large dimension, while high-resolution theory prescribes the best possible performance with a given dimension and asymptotically large bit rate.
        So vector quantization based on the Shannon rate distortion theory exploits the interdependencies of the data samples to gain performance; in especially to transmit with the same bit rate more information. With increasing dimension this interdependencies approximate the probability density function of the source. As a result the Shannon rate distortion theory leads to a small codebook with a large dimension.
        Instead vector quantization based on the high-resolution theory assumes a uniform probability density function for the source. In case of non-uniformity, a high bit rate is imposed to attain a local uniform probability density. A high bit rate means to transmit more codevectors for the same amount of information. This is resulting in a large codebook with a small dimension.

        So when dimension as well as bit rate is large, both theories merge. Obviously that each theory leads to its own design philosophy.
        Further theoretical background for both theories can be found by Gray and Neuhoff [1] and by Gersho and Gray [2].  

    1.1.1 Encoder and Decoder
        The quantization can be decomposed into two operations: a lossy encoder a and a reproduction decoder b. The lossy encoder a is the mapping from the set of source vectors X ÌRk to the index set I = {1,…,i,…N}. So a k-dimensional vectorxÎX is represented by a index iÎ I. There the set of vectors X is the infinite set of all possible combinations of k data samples. The index set I is a finite set of N indices. The reproduction decoder ? is the mapping from the index set I to the reproduction set Y ÌRk.
        To each index i is associated a reproduction vector yiÎY, whereby Y = {y1,…,yi,…,yN}. There the original set of source vectors X is partitioned in N subsets (regions) and each vector falling in a subset is represented by the associated reproduction vector. So the reproduction set Y represents with less vectors an approximation of the source.
        The reproduction set Y is also named codebook and its reproduction vectors codevectors. In fact in most vector quantization methods the reproduction set Y is used as codebook to encode and to decode the vectors as presented in Figure 1. Depending on the theory the operations encoding and decoding varies or can further be decomposed.  

    1.1.2 Distortion Measure
        The difference between the source vector and its associated codevector is the distortion (quantization error, quantization noise) measured by a cost function. Commonly used cost functions are norms so the difference between the source vector and codevector becomes a distance d. In image processing, Euclidean norm as the cost function, is the most used distortion measure. However for vector quantization the squared Euclidean norm or mean squared error is applied to simplify the computation. It has been shown that mean squared error does not correlate well with human quality requirements. In especially, details in an image such as edges and breaks getting blurred by using the mean squared error.
        Given the source vector x and the codevector yithe squared Euclidean distance or mean square error is given by
        (1-1)





    1.1.3 Codebook
        With a distortion measure and the probability density function of the source an optimal codebook can be designed. Optimal in the sense that the average distortion between each possible source vector x and the codevectors yi is minimal.
        (1-2)
        Commonly this distortion is expressed by the peak signal to noise ratio.
        (1-3)
        There the peak value is the maximal attainable source sample.
        So the codebook is partitioned such that for each vector x a nearest neighbor codevector yi exists. Mathematically spoken this partition is called Voronoi or Dirichlet partitionand the codevectors are the centroids of each region. The followingFigure 2 represents the two dimensional case.
        In general the probability density function of the source is rarely known. To circumvent this problem the rate distortion theory and high resolution theory offers each a solution.
        The later one is to choose a large number of codevectors. The associated regions are small and high structured as a lattice. So instead to find the nearest neighbor the number of codevectors is raised such that for each vector x the distortion is approximately constant. As mentioned, this results to a local uniformity of the source probability density function and a high bit rate.
        Figure 2: Codevectors in 2-dimensional space. Source vectors are marked with a cross, codevectors are marked with circles, and the Voronoi regions are separated with boundary lines. Source [27]

        The other solution is to use a training set representing best the source to optimize the codebook. To achieve this, a clustering algorithmis used. Such an algorithm is the Lloyd algorithm. It iteratively improves a codebook by alternately optimizing the encoder for the decoder - subdividing the codebook in regions (Voronoi regions) in the manner that the average distortion for the given training set is minimal, and the decoder for the encoder - replacing the codevectors by the centroids. This is repeated until the average distortion and rate converges to an inferior limit set by the Shannon rate distortion theory. So the codebook is optimal for the training set but not necessary for the set of source vectors. Other clustering algorithm are known such as the pairwise nearest neighbor algorithm by Ward and Equitz, k-means algorithm, neural net approaches, simulated annealing and stochastic relaxation algorithms just to mention some.  


    1.2 Classification of Vector Quantization
        Vector quantization can be classified into vector quantization with and without memory. Memoryless vector quantization encodes each source vector separately instead vector quantization with memory encode the source vectors exploiting in addition their interdependencies. A coarse criterion is the rate, most memoryless vector quantizations have a fixed bit rate and most vector quantizations with memory have a variable bit rate.

    1.2.1 Vector Quantization without Memory
        In practice to get reasonable vector quantization performance there are two different approaches. One remains with the original optimal vector quantization and uses fast algorithms for the nearest neighbor search. This is named as unconstrained or unstructured vector quantization. The other uses simple search algorithms and, as a consequence of the simplicity, an approximation of the optimal codebook. This is named as constrainedor structured vector quantization. Unconstrained Vector Quantization To encode a source vector the closest codevector (nearest neighbor) in the optimal codebook is determined by using different search methods. Full Search Vector Quantization For given sources vector the distortion to each codevector in the codebook is computed. The codevector with the minimal distortion is chosen as the reproduction vector. Fast Search Vector Quantization To speed up the search procedure only a subset of codevectors is used. To decide which codevectors have to be considered an inherent property of the source vectors is used. Such properties are obtained by a transformation like principal component analysis, Walsh-Hadamard transformation, discrete cosine transformation or hyperplane partitioning. An other method is to use a geometrical criterion such as the triangular inequality to exclude codevectors from the search. Constrained Vector Quantization To encode a source vector a constrained codebook is used. In this case the codevector is an approximation of the nearest neighbor vector resulting in a suboptimal encoding.

        Tree Structured Quantization The codebook is structured as a tree there beginning by the root the branches with the minimal resulting distortion are chosen.

        Classified Vector Quantization The codebook is divided in several sub-codebooks. Where the sub-codebook for a given source vectors is selected by an appropriate criterion. This criterion is based on an inherent property of the source vectors.

        Product Code Techniques The set of source vectors is divided in approximately independent subset. Each subset is encoded by its proper codebook. Depending of source different methods are used known as partitioned vector quantization, mean removed or mean residual vector quantization, shape gain vector quantization, pyramid vector quantization, polar vector quantization, multistage or residual vector quantization.

        Lattice Vector Quantization The codebook is a regular lattice there all regions having the same shape, size and orientation. begin chapter|next chapter

    1.2.2 Vector Quantization with Memory

Usually a sequence of vectors is encoded where each vector can be assumed to have the same probability density function, but the successive vectors may be statistically dependent. This is taken in advantage to raise the vector quantization performance. But low dimensional memory vector quantization does not permit performance better than high dimensional memoryless vector quantization. Predictive Vector Quantization The encoder makes a prediction of the incoming vector based on previously encoded vectors. The difference between the source vector and the predictor is formed and encoded. Finite State Vector Quantization Each state represents a separate vector quantization with its own codebook. Further vector quantization methods with memory are Entropy Vector Quantization, Tree and Trellis Vector Quantization and Adaptive Vector Quantization. A description of the above methods can be found by Gersho and Gray [2], Gray [4] and Nasrabadi and King [3]   1
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