Abstract:
Method and apparatus for the reduction of picture data for digital video signals comprising a processing of the signals by means of block by block transformation method so that a transformed and quantized signal which was generated at a time t-1 and placed in an image storage is subtracted from a transformed signal that occurs at a time t and whereby the difference signal obtained is subject to quantization and the quantized difference signal is subjected to an analysis and to a time delay which corresponds to the time requirement for the analysis for updating the content of the image storage. The signal delayed is added to the signal read out from the image storage which is also delayed and is added dependent on the addition condition signal obtained from the analysis and is subjected to an entropy coding dependent on the analysis results with the addition condition signals containing information as to whether a block which has been analyzed has been concluded is a moved or unmoved block and when the block is a moved block containing information regarding a coefficient group to be transmitted. The signal coded in such fashion is subjected to a buffering and depending on the degree of buffer filling a quantization stage and an analysis stage is influenced so that a signal from a buffer control is supplied to the quantization stage for the purpose of selecting one of a plurality of predetermined quantization characteristics and a second signal is supplied from the buffer control means to the analysis stage to select the maximum number of coefficient groups and a third signal is supplied to the analysis stage from the buffer control for the purpose of deciding whether a block is to be transmitted or not and the coefficients represent the digitized video signal transformed by block which is subdivided into coefficient groups.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for picture data reduction for digital video signals comprising a preprocessing of the signals by means of block-by-block transformation whereby a transformed and quantatized signal which was generated at a time t-1 and deposited in an image storage is subtracted from a transformed signal which occurs at a time t and whereby the difference signal obtained in such manner is subjected to a quantization. 
     2. Description of the Prior Art 
     Prior art methods for picture data reduction can be subdivided into: 
     1. DPCM (Differential Pulse Code Modulation) methods-transformation methods; and 
     2. Hybrid methods. 
     In DPCM methods, the difference between an estimate determined from samples that have already been transmitted and the actual sample is respectively identified. In pure DPCM coders, this prediction occurs three-dimensionally, in other words, both within a frame or picture as well as from frame to frame. 
     In transformation methods, an imaging of the frame into the transformation region occurs. Due to the high cost, only two dimensional transformations have previously been realized in practice. 
     The present invention relates to a hybrid method. The principles of a hybrid method is illustrated in FIG. 1. In FIG. 1, a digitized signal x (k, e, t) is supplied to a transformation stage and produces a transformation coefficient signal y(u, v, t) which is supplied to a quantitizer Q which produces a signal Ya(u, v, t) which is supplied through an adder to a coder C which produces a signal Yc(u,v,t) which is supplied as the channel signal. The output of the quantitizer Q is also supplied to a predictor and memory P+M which supplies a signal y p  (u, v,t-1) to an adder to add the signal to the output of the transformation stage before supplying it to the quantitizer Q. 
     Hybrid coding represents a mixture of transformation and DPCM. The transformation within a frame occurs two-dimensionally, block size 16×16 or 8×8 picture points, whereas DPCM operates from frame to frame. The signal decorrelated by transformation and/or DPCM is quantitized and transmitted. 
     Basically, all hybrid methods operate according to the diagram illustrated in FIG. 1. In developed methods, the functions Q, P and C are adaptively executed 
     European Patent Application No. 82.3070263 discloses a method which employs a coder having the following essential features: 
     Dynamic bit allocation--The bit rate is minimized and is selected from a plurality of Huffman code tables by means of a prediction algorithm for each coefficient to be coded. 
     Length of run coding--Zeros successively appearing along a defined scan direction are coded by lengths of run. 
     Constant Channel rate--Is achieved by coupling the quantitizer to the buffer filling. A PI controller with proportional integrating behavior is employed for this purpose. 
     The publication of F. May, &#34;Codierung von Bildfolgen mit geringer Rate fur gestorte Uebertrangungskanale&#34;, NTG-Fachberichte, Vol. 74, pp. 379-388, describes a system for picture transmission using narrow-band radio channels with a transmission rate of 9.6K bit/s and a frame frequency of 0.5 frames. A plurality of bit allocation matrices are provided for this known method so that the optimum of the respective block is identified and transmitted in the form of a class affiliation. Optimum non-linear quantization characteristics are also employed with respect to the quadratic error. A constant channel rate is achieved by input buffer control, in other words, every frame is first analyzed, the number of coeficients to be transmitted is then modified until the channel rate is observed. 
     The publication of W. H. Chen, W. K. Pratt entitled &#34;Scene Adaptive Coder&#34;, in the IEEE Trans. Comm., Vol. Com32, No. 3, of Mar. 1984, describes an adaptive band width compression technique which employs a discrete cosine transformation. This system is similar to that describes in European Patent Application No. 82.30 70 263 referenced above. 
     A publication of A. G. Tescher, entitled &#34;Rate Adaptive Communication&#34;, appearing in the IEEE International Conference on Communication, of 1978, pages 1.1-19.1.6 describes a concept for a bit rate control in a source coding system. 
     The technical book publication of W. K. Pratt entitled Image Transformation Techniques, published by the Academic Press, New York, San Francisco, and London in 1979 provides overall discussion of the transformation techniques of the systems. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a method of the species initially referenced which enables a picture quality which is improved significantly over known methods for the same or constant channel rate. In the invention, picture data reduction for digital video signals comprises preprocessing the signals using block-by-block transformation method whereby a transformed and quantitized signal that was generated at a time t-1 and placed in an image storer is subtracted from a transformed signal that occurs at a time t and whereby the difference acquired in this manner is subjected to a quantitization and the quantitized difference signal is subjected to an analysis and is subjected to a time delay VZ which corresponds to the time requirement for the analysis AS and on the one hand updating the content of the image storage and the signal which is delayed in this manner is added to the signal read out from the image storer M which is also correspondingly delayed and is added thereto dependent on the addition condition signal acquired from the analysis and on the other hand is subjected to an entropy coding HC depending on the analysis results. The addition condition signals containing information as to whether a block whose analysis has been concluded is a &#34;moved&#34; or a &#34;unmoved&#34; block and in case said block is a &#34;moved&#34; block containing information regarding a coefficient group to be transmitted, the coded signal is subjected to a buffering B which is intended to offer an output signal channel a uniform data flow for transmission and offering said uniform data flow from a nonuniform data flow of the entropy coding. Dependent on the degree of buffer filling, a quantization stage Q, an analysis stage AS is influenced so that a signal from a buffer control means BC is supplied to the quantization stage Q for selecting one of a plurality of predetermined quantization characteristics whereby a second signal is supplied from the buffer control means BC to the analysis stage AS for the purpose of selecting the maximum number of coefficient groups and where a third signal is supplied to the analysis stage AS from the buffer control means BC for deciding whether a block is to be transmitted or is not to be transmitted. The coefficients represent the digitized video signal transformed block-by-block which is subdivided into coefficient groups according to prescribed rules and a measurement scale for each of these coefficient groups is identified in a calculation stage E such that the scale first causes a supergroup to be formed in a decision means S from neighboring coefficient groups and to be transmitted and selected such that the coefficient groups which are not to be transmitted according to the identified scale can be embedded in a supergroup and by means of which a classification is executed by a following step-by-step summation of all the scales respectively belonging to a block in an integrator I where i=2 . . . 3is preferably applies and E(i) is the scale for the coefficient group i and whereby E I  (1)=E (1) applies and the classification serves the purpose for deciding whether a block is to be transmitted and what way a block to be transmitted is to be coded. 
    
    
     Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure and in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration illustrating the basic concept of prior art hybrid coding; 
     FIG. 2 is a block diagram of a complete transmission system according to a preferred exemplary embodiment according to the invention; 
     FIG. 3 is a block diagram of a transmitter of the exemplary embodiment of the transmission system shown in FIG. 2; 
     FIG. 4 is a block circuit diagram of a receiver according to the exemplary embodiment shown in FIG. 2; 
     FIG. 5a is a schematic illustration of a preferred exemplary embodiment of the manner in which a field comprising mxn coefficients is subdivided into coefficient groups in the form of imaginary diagonal strips; 
     FIG. 5b is a schematic illustration which shows how a buffer control in the method of the invention effects the coder output rate by limiting the number of coefficient groups to be transmitted; 
     FIGS. 5c and 5d show how neighboring coefficient groups are combined in a supergroup; and 
     FIGS. 6a, 6b and 6c illustrate the characteristics of a buffer control. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 2, a transmitter has a transformation stage T which transforms the signal with a discrete cosine transformation (DCT). The invention can be utilized with other transformations as well. The coding method occurs as shown in the block circuit diagrams of FIGS. 2 and 3 for the transmitter and FIGS. 2 and 4 for the receiver. As shown in FIG. 2, the transmitter has a transformation stage T which transforms the sign and supplies it to a subtractor which supplies an output to a quantizer Q. The quantizer supplies an input to an adder which supplies an output to a memory M which also supplies an input to the adder and the memory M also supplies an input to the subtractor. A coding device HC receives the output of the quantizer and also an output of an analysis stage AS which receives an input from the quantizer Q. The coding device supplies an output to the output buffer B which supplies an output to the channel encoding device. The output buffer also supplies an input to the buffer control means BC which supplies inputs to the quantizer Q and to the analysis stage AS. 
     The output of the channel encoding means of the transmitter is supplied to the receiver wherein a channel decoding means receives the incoming signal and supplies it to a receiver buffer B E  which supplies an output to a decoder DC which supplies an output to a reconstruction means R. A receiver buffer control means BC E  receives an output from the receiver buffer B E  and supplies an input to the reconstructions means R. A receiver summing means + E  receives the output of the reconstruction means and also an input from the decoder DC. The receiver summing means supplies an output to the innertransformation stage IT which produces the reconstructed signal. The receiver summing means + E  also supplies an input to a receiver image storer M E  which supplies an input to the receiver summing element. 
     FIG. 3 illustrates in greater detail portions of the transmitter where the output of the transformation stage T is supplied to the subtractor which supplies an output to the quantizer Q which supplies an output to the first time delay VZ which supplies an output to the entropy coding device HC. An adder also receives output from the first time delay VZ as well as an output of a decision means S and an output of a classification device K. The adder supplies an output to a memory M which supplies an output to the subtractor. A second time delay VZ receives the output of the memory and supplies an input to the adder. The analysis stage AS comprises a calculation stage E which receives the output of the quantizer Q and supplies an input to a first network L1 and a second network L2. A decision means S receives the output of the first network L1 as well as an input N DMAX  from the buffer control BC. An integrator I receives the output of the second network L2 and supplies an input to the classification stage K which receives an input T from the buffer control BC as well as an input N DMAX  from the buffer control BC. The buffer control also supplies an input ≠ to the quantizer Q as illustrated. The entropy coding device HC supplies an output to the output buffer B which produces the output channel signal which is to be transmitted and also supplies an input to the buffer control BC. 
     The receiver buffer BE receives the incoming channel signal and supplies it to a decoder DC which supplies an output to the reconstruction means R. A receiver buffer control means BC E  receives an output from the receiver buffer B E  and supplies an input to the reconstruction means R. The decoder DC supplies an input to a receiver summing means + E  which also receives the output of reconstruction means R. The transformed signal appears at the output of the receiver summing means + E  and the output of the receiver summing means + E  is supplied to a receiver image storer M E  which also supplies an input to the receiver summing means +E. 
     The incoming frames are two-dimensionally cosine transformed in blocks (block size 16×16 picture points). The block size 8×8 can be simply realized by modification of Huffman code tables 1B and of the bit allocation matrices, Table 2 attached. The difference between the spectral coefficients thus obtained and the corresponding coefficients in the DPCM memory M is then quantized in block Q according to the quantization interval Δ determined by the buffer control. 
     The energy calculation stage E is then defined for each coefficient group as illustrated in FIG. 5A from the quanzation prediction error signal Δy Q  (u, v, t). ##EQU1## 
     It is assured by the limit function f A  (x) that the result t of ΔY Q   2  is not represented with more bits than needed for further processing. The accumulator employed for the summation likewise has only twelve bits whereby a thirteenth bit is set to &#34;1&#34; and remains as soon as overflow has once occured. 
     The energies E(i) obtained in this manner are forwarded to the decision means S through a network L1. L1 limits the amplitude range to E*(i)·(0≦E*(i)≦16) so that E*(i) can be represented with 5 bits. 
     Whether a coefficient group is to be transmitted is determined in the stage S for every coefficient group on the basis of its energy by comparison to thresholds deposited in table form. The number of the first coefficient group to be transmitted supplies N O  whereas the number of the last coefficient group to be transmitted supplies N D . When N O  &lt;4 then it is equated with &#34;1&#34;. In case no coefficient group to be transmitted has been found, N O  and N D  are equated with &#34;1&#34;. It is therefore assured that the block is classified as unmoved given the classification K as well. The buffer control can influence the rate by assigning the maximum plurality of coefficient groups. 
     In case that N D  is greater than a value N DMAX  prescribed by the buffer control, then ND=N DMAX  is to be set. 
     The output of the decision means S is forwarded for classification K to the classification means K and to a coding means HC and to a conditioned adder (+). 
     The output of the calculation stage E supplies the energies E(i) to an integrator I through a network L2 which cuts off or truncates the least four significant bits. The integrator forms the signal EI(i) from E(i) according to the following equation. 
     E I  (i)=E I  (i-1)+E(i)                             i=2 2, . . . , 31 and E I  (1)=E(1)                                   (2 ) 
     Only the bits having the significance of 0 . . . 7 are thereby taken into consideration in the addition, whereas bit 8, OR-operated with the overflow bit of the adder, yields the bit 8 of the accumulator, so that 9-bit code words are again present at the output of the integrator I. 
     The classification stage K executes the following operations: 
     
         E.sub.I (N.sub.D)&gt;T (barrier T=0,1,2,3 prescribed by the buffer control) → block moved 
    
     
         E.sub.I (N.sub.D)≦T→block unmoved            (3) 
    
     By cutting off or truncating the four least-significant bits in the energy calculation, the four values of the barrier or threshold T specified in the relationship of equation (3) result from FIG. 6a as shown by curve K1. 
     When the block is unmoved, it is assigned to the &#34;unmoved&#34; class 4. When the block is moved and thus, is to be transmitted, then the energy of the supergroup to be transmitted is defined as: ##EQU2## and with the assistance of E G , the block is assigned to one of three &#34;moved&#34; classes. 
     The two necessary class boundaries G(N O , N D , 1) and G(N O , N D , 2) are identified in the following fashion: ##EQU3## where E H  is the mean energy variance presumed in the generation of the Huffman code tables B(i, j, k) is the allocation matrix f of the Huffman code tables for class K (table 2), 
     E Hg  is the energy up to the diagonal N D  averaged over class k and k+1. ##EQU4## 
     The case discrimination and the calculation of G(N O , N D ,k) and E G  results that the like component in all classes is coded with the same Huffman code table for maximum variance. Its energy therefore remains unconsidered in the classification. The supergroup to be transmitted is then coded in the entropy coding means HC and written into the output buffer B. The code tables 1-7 of table 1 are employed therefore and these being selected for every coefficient via the allocation matrices in table 2. So-called &#34;modified&#34; Huffman codes are employed in the coding. Values /y/≦y esc  are thereby Huffman-coded. Given /y/&gt;y esc , an escape word is transmitted followed by the value of y in the natural code. The quantization interval can assume the values Δ o , Δ o  /2,Δ o  /4,Δ o  /8. Amplitude levels of 255, 511, 1023 and 2047 correspond to these values. These natural code words therefore have different lengths (8, 9, 10, 11 bits). 
     The class affiliation and the supergroup (N O , N D ) must be additionally transmitted for every block. The following bit rates are required for this overhead: 
     First case: 2 bits when k=4 (&#34;unmoved&#34; class) 
     Second case: 2 bits + the average word length indicated in table 1B (&#34;Huffman&#34; code tables for supergroup and class when k=1 through 3. 
     Last, the DPCM memory is brought to the current reading. The supergroup and the class affiliation are therefore to be considered as: ##EQU5## Y&#39;(u,v,t)=Y&#39;(u,v,t-1)+Δy Q  (u,v t) otherwise. 
     (Buffer Control) 
     As set forth above, a constant channel rate is achieved by modification of the barrier &#34;moved&#34;/&#34;unmoved&#34; T, of the quantization interval Δ and of the diagonal N DMAX  to be maximally transmitted. The values T, Δ, N DMAX  illustrated in FIG. 6b are identified by the non-linear characteristics K1 through K3 depending on the filling of the buffer. 
     In the region B n  &lt;B(k)≦1 (characteristic K3), the rate is controlled via N DMAX . 
     No control results for BΔ≦B(k)≦1. When 0≦B(k)&lt;BΔ occurs, then the buffer control results via the quantization interval Δ shown in FIG. 6c. Δ can thereby only assume values that meet the following inequality. 
     
         0≦int (1dΔo/Δ))≦3                (8) 
    
     As previously set forth, the quantization interval must also be considered in the coding. 
     Assuming a very full buffer B(k)&gt;B T  illustrated by the characteristic K1 in FIG. 6a, the barrier T is also raised by a quadratic characteristic K1. The raising of the barrier &#34;moved&#34;/&#34;unmoved&#34; then occurs in two ways: 
     (a) increase of T by the characteristic K1 
     (b) reduction of N DMAX  and, thus, of the total energy (E G ) by characteristic K3. 
     A very efficient noise suppression with full buffer is achieved by means of (b). 
     Significant innovations over known methods of the present invention are: 
     (1) Buffer Control 
     Way of limiting the bit rate by omitting coefficient groups when the buffer runs full. The number of coefficient groups is therefore controlled with a proportional controller. 
     Control of the rate by way of the quantization interval given a buffer running empty with a proportional controller. The quantization interval can therefore only assume the values of Δ o , Δ o  /2,Δ o  /4,Δ o  /8. 
     Way of recognizing altered blocks by calculation of the energy of the quantitized signal. This is identical to a coupling of the &#34;moved&#34;/&#34;unmoved&#34; T to the quantization interval. A good value for T is T=N 2  /12. This T is constant over a wide range of the buffer filling. 
     Raising the barrier T given buffer running full by way of a quadratic characteristic. 
     The controller for the number of diagonals to be maximally transmitted and the controller for the quantization interval never work in common but only respectively one operates dependent on the fill of the buffer. 
     The fact that only the coefficient groups that are transmitted are taken into consideration for the modification recognition for blocks is an advantage. 
     2. Coding 
     Adaptive Huffman coding by fixed allocation of the Huffman code tables for three &#34;moved&#34; categories (previously there has been dynamic allocation of the Huffman code tables (HCT) /1/ and fixed allocation of non-linear optimum n-bit maxquantizers /2/). 
     Classification on the basis of the quantized signal. 
     Way of identifying the class boundaries from the allocation of the Huffman code tables and the variance for which the HCT are generated. 
     Way of recognizing and coding modified supergroups within a block (in /1/, by length of run coding and end of block code word). 
     The fact that only the coefficient groups that are transmitted are considered for the modified recognition of blocks. 
     The tables which are utilized in this invention follow. 
     
                       TABLE 1______________________________________Huffman Code Table______________________________________(A) For CoefficientsGiven code word numbers unequal to zero and Huffman codeof the Operation sign is appended to the tables:(1) Less Than Zero VZ = 1(2) Greater Than Zero VZ = 0(The code word length in the corresponding code words istherefore greater than the length of the code in the table.)Code Table Number:           1Number of words:           511Scanner:        0.75Residual Probability           0.00100Actual Residual Probility           0.00021Mean Word Length:           1.8520Entropy:        1.6386______________________________________Code Word Number       Huffman Code                   Word Length                              Probability______________________________________0               0           1        0.6097491               10          3        0.1654092               110         4        0.0251913               1110        5        0.0038374               11110       6        0.0005845    Escape Word           11111       14       0.0000896               ESC         14       0.0000147               ESC         14       0.0000028               ESC         14       0.0000009               ESC         14       0.00000010              ESC         14       0.000000and so forth until NW/2 = 255______________________________________Code Table Number           2Number of words 511Scanner         1.50Residual Probability           0.00100Actual Residual Probability           0.00086Mean Word Length           2.6491Entropy         2.5680______________________________________Code Word Number       Huffman Code                   Word length                              Probability______________________________________0               00          2        0.3752991               1           2        0.1904552               010         4        0.0743253               0110        5        0.0290064               01110       6        0.0113195               011110      7        0.0044176               0111110     8        0.0017247               01111110    9        0.0006738    Escape Word           01111111    17       0.0002639               ESC         17       0.00010210              ESC         17       0.00004011              ESC         17       0.00001612              ESC         17       0.00000613              ESC         17       0.000002and so forth until NW/2 = 255______________________________________Code Table Number:           3Number of Words:           511Scanner:        3.00Residual Probability           0.00100Actual Residual Probability           0.00068Entropy         3.5416______________________________________Code Word Number       Huffman Code                   Word Length                              Probability______________________________________0               00          2        0.2096201               10          3        0.1483142               110         4        0.0926523               010         4        0.0578804               1110        5        0.0361585               0110        5        0.0225886               11110       6        0.0141117               01110       6        0.0088158               111110      7        0.0055079               011110      7        0.00344010              1111110     8        0.00214911              0111110     8        0.00134212              11111110    9        0.00083913              01111110    9        0.00052414              111111110   10       0.00032715              111111111   10       0.00020416   Escape Word           01111111    17       0.00012817              ESC         17       0.00008018              ESC         17       0.00005019              ESC         17       0.00003120              ESC         17       0.00001921              ESC         17       0.000012and so forth until NW/2 = 255______________________________________Code Table Number:           4Number of Words:           511Scanner:        6.00Residual Probability           0.00800Actual Residual Probability           0.00636Mean Word Length           4.5988Entropy:        4,5335______________________________________0               000         3        0.1109671               01          3        0.0931792               100         4        0.0736473               110         4        0.0582094               1010        5        0.0460075               1110        5        0.0363636               0010        5        0.0287417               10110       6        0.0227168               11110       6        0.0179549               00110       6        0.01419110              101110      7        0.01121611              111110      7        0.00886512              001110      7        0.00700713              1011110     8        0.00553814              1111110     8        0.00437715              0011110     8        0.00346016              10111110    9        0.00273417              11111110    9        0.00216118              101111110   10       0.00170819              101111111   10       0.00135020              111111110   10       0.00106721              111111111   10       0.00084322   Escape Word           0011111     16       0.00066723              ESC         16       0.00052724              ESC         16       0.00041625              ESC         16       0.00032926              ESC         16       0.00026027              ESC         16       0.000206and so forth until NW/2 = 255______________________________________Code Table Number:           5Number of Words:           511Scanner:        12.00Residual Probability           0.00800Actual Residual Probability           0.00759Mean Word Length           5.5889Entropy         5.5313______________________________________0               0000        4        0.0571141               001         4        0.0523142               010         4        0.0465093               1000        5        0.0413484               1010        5        0.0367605               1100        5        0.0326816               1110        5        0.0290547               0110        5        0.0258308               10010       6        0.0229649               10110       6        0.02041610              11010       6        0.01815011              11110       6        0.01613612              00010       6        0.01434613              01110       6        0.01275414              100110      7        0.01133915              101110      7        0.01008016              110110      7        0.00896217              111110      7        0.00796718              000110      7        0.00708319              011110      7        0.00629720              1001110     8        0.00559821              1011110     8        0.00497722              1101110     8        0.00442523              1111110     8        0.00393424              0001110     8        0.00349725              0111110     8        0.00310926              10011110    9        0.00276427              10111110    9        0.00245728              11011110    9        0.00218529              00011110    9        0.00194230              00011111    9        0.00172731              01111110    9        0.00153532              100111110   10       0.00136533              101111110   10       0.00121334              101111111   10       0.00107935              110111110   10       0.00095936              011111110   10       0.00085337              011111111   10       0.00075838              1001111110  11       0.00067439              1001111111  11       0.00059940              1101111110  11       0.00053341              1101111111  11       0.00047442   Escape Word           1111111     16       0.00042143              ESC         16       0.00037444              ESC         16       0.00033345              ESC         16       0.00029646              ESC         16       0.00026347              ESC         16       0.000234and so forth until NW/2 = 255______________________________________Code Table Number:           6Number of Words:           511Scanner:        24.00Residual Probability           0.01000Actual Residual Probability           0.00989Mean Word Length:           6.5860Entropy:        6.5307______________________________________Code Word Number       Huffman Code                   Word Length                              Probability______________________________________0               00000       5        0.0289761               0001        5        0.0277292               0010        5        0.0261453               0100        5        0.0246524               0110        5        0.0232445               10000       6        0.0219176               10010       6        0.0206657               10100       6        0.0194858               10110       6        0.0183729               11000       6        0.01732310              11010       6        0.01633311              11100       6        0.01540012              11110       6        0.01452113              00110       6        0.01369214              01010       6        0.01291015              01110       6        0.01217216              100010      7        0.01147717              100110      7        0.01082218              101010      7        0.01020319              101110      7        0.00962120              110010      7        0.00907121              110110      7        0.00855322              111010      7        0.00806523              111110      7        0.00760424              000010      7        0.00717025              001110      7        0.00676026              010110      7        0.00637427              011110      7        0.00601028              1000110     8        0.00566729              1001110     8        0.00534330              1010110     8        0.00503831              1011110     8        0.00475032              1100110     8        0.00447933              1101110     8        0.00422334              1110110     8        0.00398235              1111110     8        0.00375536              0000110     8        0.00354037              0011110     8        0.00333838              0101110     8        0.00314739              0111110     8        0.00296840              10001110    9        0.00279841              10001111    9        0.00263842              10011110    9        0.00248843              10111110    9        0.00234644              11001110    9        0.00221245              11011110    9        0.00208546              11101110    9        0.00196647              11111110    9        0.00185448              00001110    9        0.00174849              00111110    9        0.00164850              00111111    9        0.00155451              01011110    9        0.00146552              01111110    9        0.00138253              100111110   10       0.00130354              101111110   10       0.00122855              110011110   10       0.00115856              110111110   10       0.00109257              110111111   10       0.00103058              111011110   10       0.00097159              111111110   10       0.00091560              000011110   10       0.00086361              000011111   10       0.00081462              010111110   10       0.00076763              011111110   10       0.00072365              1001111111  11       0.00064366              1011111110  11       0.00060667              1100111110  11       0.00057268              1100111111  11       0.00053969              1110111110  11       0.00050870              1110111111  11       0.00047971              1111111110  11       0.00045272              1111111111  11       0.00042673              0101111110  11       0.00040274              0101111111  11       0.00037975              0111111110  11       0.00035776              0111111111  11       0.00033777              10111111110 12       0.00031878              10111111111 12       0.00029979   Escape Word           1010111     16       0.00028280              ESC         16       0.00026681              ESC         16       0.00025182              ESC         16       0.00023783              ESC         16       0.00022384              ESC         16       0.000210and so forth until NW/2 = 255______________________________________Code Table Number:           7Number of Words:           511Scanner:        48.00Residual Probability           0.03000Actual Residual Probability           0.02943Mean Word Length           7.6155Entropy:        7.5384______________________________________Code Word Number       Huffman Code                   Word Length                              Probability______________________________________0               000000      6        0.0144531               00010       6        0.0141412               00100       6        0.0137353               00110       6        0.0133424               00111       6        0.0129595               01000       6        0.0125876               01010       6        0.0122267               01100       6        0.0118768               01110       6        0.0115359               100000      7        0.01120410              100010      7        0.01088311              100100      7        0.01057112              100110      7        0.01026813              101000      7        0.00997314              101010      7        0.00968715              101100      7        0.00940916              101110      7        0.00913917              110000      7        0.00887718              110010      7        0.00862319              110100      7        0.00837520              110110      7        0.00813521              111000      7        0.00790222              111010      7        0.00767523              111100      7        0.00745524              000001      7        0.00724125              000010      7        0.00703426              000110      7        0.00683227              001010      7        0.00663628              010010      7        0.00644629              010110      7        0.00626130              011010      7        0.00608131              011110      7        0.00590732              1000010     8        0.00573733              1000110     8        0.00557335              1001110     8        0.00525836              1010010     8        0.00510737              1010110     8        0.00496138              1011010     8        0.00481839              1011011     8        0.00468040              1011110     8        0.00454641              1100010     8        0.00441642              1100110     8        0.00428943              1101010     8        0.00416644              1101110     8        0.00404645              1110010     8        0.00393046              1110110     8        0.00381847              1111010     8        0.00370848              0000110     8        0.00360249              0001110     8        0.00349850              0010110     8        0.00339851              0100110     8        0.00330152              0100111     8        0.00320653              0101110     8        0.00311454              0110110     8        0.00302555              0111110     8        0.00293856              10000110    9        0.00285457              10001110    9        0.00277258              10010110    9        0.00269259              10011110    9        0.00261560              10011111    9        0.00254061              10100110    9        0.00246762              10101110    9        0.00239763              10111110    9        0.00232864              11000110    9        0.00226165              11001110    9        0.00219666              11010110    9        0.00213367              11011110    9        0.00207268              11011111    9        0.00201369              11100110    9        0.00195570              11101110    9        0.00189971              11110110    9        0.00184472              00001110    9        0.00179273              00011110    9        0.00174074              00101110    9        0.00169075              00101111    9        0.00164276              01011110    9        0.00159577              01101110    9        0.00154978              01111110    9        0.00150579              01111111    9        0.00146180              100001110   10       0.00141981              100011110   10       0.00137982              1001k01110  10       0.00133983              1001011111  10       0.00130184              101001110   10       0.00126385              101011110   10       0.00122786              101111110   10       0.00119287              101111111   10       0.00115888              110001110   10       0.00112589              110011110   10       0.00109290              110101110   10       0.00106191              110101111   10       0.00103192              111001110   10       0.00100193              111011110   10       0.00097294              111101110   10       0.00094495              111101111   10       0.00091796              000011110   10       0.00089197              000111110   10       0.00086698              000111111   10       0.00084199              010111110   10       0.000817100             010111111   10       0.000793101             011011110   10       0.000770102             011011111   10       0.000748103             1000011110  11       0.000727104             1000011111  11       0.000706105             1000011110  11       0.000686106             1000111111  11       0.000666107             1010011110  11       0.000647108             1010011111  11       0.000628109             1010111110  11       0.000610110             1010111111  11       0.000593111             1100011110  11       0.000576112             1100011111  11       0.000559113             1100111110  11       0.000543114             1100111111  11       0.000528115             1110011110  11       0.000513116             1110011111  11       0.000498117             1110111110  11       0.000484118             1110111111  11       0.000470119             0000111110  11       0.000456120             0000111111  11       0.000443121  Escape Word           11111       14       0.000431122             ESC         14       0.000418123             ESC         14       0.000406124             ESC         14       0.000395125             ESC         14       0.000383126             ESC         14       0.000372and so forth until NW/2 = 255______________________________________(B) Code tables for transmitted subregion and class affiliation:11 unmoved class00 Greatest Detail content01 Mean Detail content10 Smallest Detail contentIn the moved classes subregion is codes as follows:(1) N.sub.O = 1No. of diagonals equal code word number in&#34;Huffman Code Table for subregion(2) Code Word number 32 escape word for:N.sub.D &gt; 16 and simultaneous N.sub.O ≧ 4Escape word is transmitted first and N.sub.D is then transmittedwith 4 bits and N.sub.O transmitted with 5 bits total 16 bits.(3) Following Table valid for4 ≦ N.sub.O ≦ 16 and simultaneous 4 ≦ N.sub.D≦ 16The code word number in &#34;Huffman code table for subregion&#34;Possible combination for ND and NO then for subregions.______________________________________NO↓ND→ 4  5  6  7  8  9 10              11     12   13   14   15   16 4   33 34 35 36 37 38 39              40     41   42   43   44   45 5   46 47 48 49 50 51              52     53   54   55   56   57 6   58 59 60 61 62              63     64   65   66   67   68 7   69 70 71 72   73     74   75   76   77   78 8   79 80 81      82     83   84   85   86   87 9   88 89         90     91   92   93   94   9510   96            97     98   99   100  101  10211                 103    104  105  106  107  10812                        109  110  111  112  11313                             114  115  116  11714                                  118  119  12015                                       121  12216                                            123______________________________________Huffman Code Table for subregionDivision Content:       6.94251Entropy:    5.29115Mid word length       5.34360______________________________________Code Word Number       Huffman Code                   Word Length                              Probability______________________________________1               0000        4        0.0555312               0100        4        0.0555313               0101        4        0.0555314               0110        4        0.0555315               0111        4        0.0555316               1000        4        0.0555317               1001        4        0.0555318               1010        4        0.0555319               1011        4        0.05553110              1100        4        0.05553111              00010       5        0.02776612              11010       5        0.02776613              11011       5        0.02776614              11100       5        0.02776615              11101       5        0.02776616              11110       5        0.02776617              000110      6        0.01388318              111110      6        0.01388319              00011100    8        0.00347120              00011110    8        0.00347121              0001110100  10       0.00086822              0001110110  10       0.00086823              0001110111  10       0.00086824              0001111100  10       0.00086825              00011101010 11       0.00043426              00011111010 11       0.00043427              00011111011 11       0.00043428              00011111100 11       0.00043429              00011111101 11       0.00043430              00011111110 11       0.00043431              00011111111 11       0.00043432              1111110     7        0.00694133              001000      6        0.02776634              1111111     7        0.00694135              00100100    8        0.00694136              001001010   9        0.00347137              001001011   9        0.00347138              001001100   9        0.00347139              001001101   9        0.00347140              001001110   9        0.00347141              0010011110  10       0.00173542              0010011111  10       0.00173543              00101000000 11       0.00086844              00101000001 11       0.00086846              0010101     7        0.01388347              00101001    8        0.00694148              001010001   9        0.00347149              001011000   9        0.00347150              001011001   9        0.00347151              0010110100  10       0.00173552              00101000011 11       0.00086853              00101101010 11       0.00086854              00101101011 11       0.00086855              00101101100 11       0.00086856              001010000101                       12       0.00043457              001011011010                       12       0.00043458              0010111     7        0.01388359              001100000   9        0.00347160              001100001   9        0.00347161              001100010   9        0.00347162              0010110111  10       0.00173563              00110001100 11       0.00086864              00110001101 11       0.00086865              00110001110 11       0.00086866              00110001111 11       0.00086867              001011011011                       12       0.00043468              001100100000                       12       0.00043469              0011010     7        0.01388370              001100101   9        0.00347171              001100110   9        0.00347172              0011001001  10       0.00173573              00110010001 11       0.00086874              00110011100 11       0.00086875              00110011101 11       0.00086876              00110011110 11       0.00086877              001100100001                       12       0.00043478              001100111110                       12       0.00043479              00110110    8        0.00694180              001101110   9        0.00347181              0011011110  10       0.00173582              00110111110 11       0.00086883              00110111111 11       0.00086884              00111000000 11       0.00086885              00111000001 11       0.00086886              001100111111                       12       0.00043487              001110000100                       12       0.00043488              00111001    8        0.00694189              0011100010  10       0.00173590              00111000011 11       0.00086891              00111000110 11       0.00086892              00111000111 11       0.00086893              00111010000 11       0.00086894              001110000101                       12       0.00043495              001110100010                       12       0.00043496              00111011    8        0.00694197              00111010010 11       0.00086898              00111010011 11       0.00086899              00111010100 11       0.000868100             00111010101 11       0.000868101             001110100011                       12       0.000434102             001110101100                       12       0.000434103             00111000    9        0.003471104             00111010111 11       0.000868105             00111100100 11       0.000868106             00111100101 11       0.000868107             001110101101                       12       0.000434108             001111001100                       12       0.000434109             001111010   9        0.003471110             00111100111 11       0.000868111             00111101100 11       0.000868113             001111011010                       12       0.000434114             001111100   9        0.003471115             00111101110 11       0.000868116             001111011011                       12       0.000434117             001111011110                       12       0.000434118             001111101   9        0.003471119             001111011111                       12       0.000434120             000111010110                       12       0.000434121             001111110   9        0.003471122             000111010111                       12       0.000434123             001111111   9        0.003471______________________________________ 
    
     
                       TABLE 2______________________________________Allocation Matrices Fixed Allocation Huffman CodeTable for the Three Moved Classes______________________________________CLASS 17 6 5 4 4 3 3 3 2 2 2 2 1 1 1 16 5 4 4 3 3 3 2 2 2 2 1 1 1 1 15 4 4 3 3 3 2 2 2 2 1 1 1 1 1 14 4 3 3 3 2 2 2 2 1 1 1 1 1 1 14 3 3 3 2 2 2 2 1 1 1 1 1 1 1 13 3 3 2 2 2 2 1 1 1 1 1 1 1 1 13 3 2 2 2 2 1 1 1 1 1 1 1 1 1 13 2 2 2 2 1 1 1 1 1 1 1 1 1 1 12 2 2 2 1 1 1 1 1 1 1 1 1 1 1 12 2 2 1 1 1 1 1 1 1 1 1 1 1 1 12 2 1 1 1 1 1 1 1 1 1 1 1 1 1 12 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1CLASS 27 5 4 3 3 2 2 2 1 1 1 1 1 1 1 15 4 3 3 2 2 2 1 1 1 1 1 1 1 1 14 3 3 2 2 2 1 1 1 1 1 1 1 1 1 13 3 2 2 2 1 1 1 1 1 1 1 1 1 1 13 2 2 2 1 1 1 1 1 1 1 1 1 1 1 12 2 2 1 1 1 1 1 1 1 1 1 1 1 1 12 2 1 1 1 1 1 1 1 1 1 1 1 1 1 12 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1CLASS 37 4 3 2 2 1 1 1 1 1 1 1 1 1 1 14 3 2 2 1 1 1 1 1 1 1 1 1 1 1 13 2 2 1 1 1 1 1 1 1 1 1 1 1 1 12 2 1 1 1 1 1 1 1 1 1 1 1 1 1 12 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1______________________________________ 
    
     Although the invention has been described with respect to preferred embodiments, it is not to be so limited as changes and modifications can be made which are within the full intended scope of the invention as defined by the appended claims.