USRE37091EExpiredUtilityPatentIndex 72
Motion compensated prediction interframe coding system
Assignee: MATSUSHITA ELECTRIC INDUSTRIAL CO LTDPriority: Oct 13, 1989Filed: Aug 31, 1994Granted: Mar 13, 2001
Est. expiryOct 13, 2009(expired)· nominal 20-yr term from priority
H04N 19/82H04N 19/159H04N 19/176H04N 19/15H04N 19/61H04N 19/60H04N 19/107H04N 19/126H04N 19/14H04N 19/146
72
PatentIndex Score
13
Cited by
7
References
33
Claims
Abstract
A motion compensated prediction interframe coding system which first measures characteristics regarding the fineness of a pattern or texture of a picture, which is represented by an input television signal and is divided into a group of continuous blocks each quantized by using a quantization step size, and changes the quantization step size into a smaller one if quantizes a block having a picture pattern or texture finer than patterns of the other blocks. Thereby, an amount of generated codes can be limited but a motion compensated prediction frame coding operation can be performed without degrading the fineness of the texture of the original input picture.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1. A motion compensated prediction interframe coding system comprising:
an analog-to-digital conversion means for performing an analog-to-digital conversion of a television signal;
a block dividing means for dividing a predetermined area of the television signal digitalized by said analog-to-digital conversion means into blocks each having a predetermined size;
a motion vector calculating means for calculating a motion vector, which represents a motion of a television picture represented by the television signal, of each block and for judging with respect to each block whether or not the motion compensation is performed by using by the motion vector;
a motion compensation means for performing a motion compensation of a reproduced picture signal of a previous frame with respect to each block of which the motion compensation is determined by said motion vector calculating means to be effected and for calculating predicted gray levels of pixels of each block of which the motion compensation is effected;
a prediction error evaluating means for computing the difference between the gray level of each pixel of a coding block of the television picture and the predicted gray level thereof as a prediction error thereof;
an orthogonal transform means for performing an orthogonal transform of the prediction error of each pixel of a coding block of the television picture so as to obtain orthogonal transform coefficients;
a first quantization step-size computing means for computing a first step size for the quantization from an amount of generated codes;
a variance calculating means for calculating a variance of the gray levels of the pixels of each block of input television signal;
a second quantization step-size computing means for classifies the blocks into a predetermined number of classes according to the variance and computing a second step size for the quantization of each block from the first step size;
a quantization means for quantizing coefficients of an orthogonal transform by using the second step size to obtain quantized coefficients of orthogonal transform;
an orthogonal transform coefficient coding means for performing the coding of the prediction error, the first step size and information on the classes and the quantized coefficients of the orthogonal transform;
a quantized prediction error calculating means for effecting an inverse orthogonal transform of the quantized coefficients of the orthogonal transform to obtain quantized prediction errors;
a reproduced picture calculating means for calculating a reproduced picture from the quantized prediction errors and the predicted gray levels of the pixels of the blocks;
a memory portion for storing the reproduced picture; and
a motion vector coding means for performing the coding of the motion vectors.
2. A motion compensated prediction interframe coding system as set forth in claim 1 wherein the predetermined area is one frame.
3. A motion compensated prediction interframe coding system as set forth in claim 1 wherein the predetermined area is one field.
4. A motion compensated prediction interframe coding system comprising:
an analog-to-digital conversion means for performing an analog-to-digital conversion of a television signal;
a block dividing means for dividing a predetermined area of the television signal digitalized by said analog-to-digital conversion means into blocks each having a predetermined size;
a motion vector calculating means for calculating a motion vector, which represents a motion of a television picture represented by the television signal, of each block and for judging with respect to each block whether or not the motion compensation is performed by using by the motion vector;
a motion compensation means for performing a motion compensation of a reproduced picture signal of a previous frame with respect to each block of which the motion compensation is determined by said motion vector calculating means to be effected and for calculating predicted gray levels of pixels of each block of which the motion compensation is effected;
a prediction error evaluating means for computing the difference between the gray level of each pixel of a coding block of the television picture and the predicted gray level thereof as a prediction error thereof;
a coding method selection means for selecting a method of coding of a block from an interframe coding and intraframe coding methods;
a first switch means for selecting a signal, of which an orthogonal transform is effected, in accordance with the selection made by said coding method selecting means from the gray levels of pixels of blocks represented by the television signal and the prediction errors;
an orthogonal transform means for performing an orthogonal transform of the prediction error or the gray levels selected by said first switch means;
a first quantization step-size computing means for computing a first step size for the quantization from an amount of generated codes;
a variance calculating means for calculating a variance of the gray levels of the pixels of each block of input television signal;
a second quantization step-size computing means for classifying the blocks into a predetermined number of classes according to the variance and computing a second step size for the quantization of each block from the first step size in case of the blocks to be coded by using an intra-frame coding method and for treating the first step sizes as the second step sizes in case of the blocks to be coded by using an interframe coding method;
a quantized transform coefficient calculating means for quantizing coefficients of an orthogonal transforms by using the second step size to obtain quantized coefficients of an orthogonal transform;
an orthogonal transform coefficient coding means for performing information on the selection of the coding methods, the coding of the prediction error, the first step size and information on the classes and the quantized coefficients of the orthogonal transform;
an inverse quantization means for effecting an inverse orthogonal transform of the quantized coefficients of the orthogonal transform to obtain inversely-quantized values;
a second switch means for selecting a numerical value of zero as a gray level of a pixels of a reproduced picture in case where said coding method selection means selects the intraframe coding method and in contrast, selects the predicted value as the gray level of a pixel of the reproduced picture in case where the coding method selection means selects the interframe coding method;
a reproduced picture calculating means for calculating a reproduced picture from the inversely-quantized values and the numerical value of zero or from the predicted gray levels of the pixels of the blocks;
a memory portion for storing the reproduced picture; and
a motion vector coding means for performing the coding of the motion vectors.
5. A motion compensated prediction interframe coding system as set forth in claim 4 wherein the predetermined area, is one frame.
6. A motion compensated prediction interframe coding system as set forth in claim 4 wherein the predetermined area is one field.
7. A motion compensated prediction interframe coding system comprising:
an analog-to-digital conversion means for performing an analog-to-digital conversion of a television signal;
a block dividing means for dividing a predetermined area of the television signal digitalized by said analog-to-digital conversion means into blocks each having a predetermined size;
a motion vector calculating means for calculating a motion vector, which represents a motion of a television picture represented by the television signal, of each block and for judging with respect to each block whether or not a motion compensation prediction is performed by using by the motion vector;
a motion compensation predicting means for performing a motion compensation prediction of a reproduced picture signal of a previous frame with respect to each block of which the motion compensation prediction is determined by said motion vector calculating means to be effected and for calculating predicted gray levels of pixels of each block of which the motion compensation prediction is effected;
a prediction error evaluating means for computing the difference between the gray level of each pixel of a coding block of the television picture and the predicted gray level thereof as a prediction error thereof;
a coding method selection means for selecting a method of coding of a block from an interframe coding and intraframe coding methods;
a first switch means for selecting a signal, of which an orthogonal transform is effected, in accordance with the selection made by said coding method selecting means from the gray levels of pixels of blocks represented by the television signal and the prediction errors;
an orthogonal transform means for performing an orthogonal transform of the prediction error or the gray levels selected by said first switch means;
a first quantization step-size computing means for computing a first step size for the quantization from an amount of generated codes;
an average and variance calculating means for calculating an averaged value and a variance of the gray levels of the pixels of each block of input television signal;
a second quantization step-size computing means for classifying the blocks into a predetermined number of classes according to the averaged value and variance and computing a second step size for the quantization of each block from the first step size in case of the blocks to be coded by using an intra-frame coding method and for treating the first step sizes as the second step sizes in case of the blocks to be coded by using an interframe coding method;
a quantized transform coefficient calculating means for quantizing coefficients of an orthogonal transform by using the second step size to obtain quantized coefficients of an orthogonal transform;
an orthogonal transform coefficient coding means for performing information on the selection of the coding methods, the coding of the prediction error, the first step size and information on the classes and the quantized coefficients of the orthogonal transform;
an inverse quantization means for effecting an inverse orthogonal transform of the quantized coefficients of the orthogonal transform to obtain inversely-quantized values;
a second switch means for selecting a numerical value of zero or the predicted gray level obtained by the motion compensation prediction as a gray level of a pixels of a reproduced picture according to the selection made by said coding method selection means;
a reproduced picture calculating means for calculating a reproduced picture from the inversely-quantized values and the numerical value of zero or from the predicted gray levels of the pixels of the blocks;
a memory portion for storing the reproduced picture; and
a motion vector coding means for performing the coding of the motion vectors.
8. A motion compensated prediction interframe coding system as set forth in claim 7 wherein the predetermined area is one frame.
9. A motion compensation prediction interframe coding system as set forth in claim 7 wherein the predetermined area is one field.
10. A motion compensated prediction interframe coding system comprising:
an analog-to-digital conversion means for performing an analog-to-digital conversion of a television signal;
a block dividing means for dividing a predetermined area of the television signal digitalized by said analog-to-digital conversion means into blocks each having a predetermined size;
a motion vector calculating means for calculating a motion vector, which represents a motion of a television picture represented by the television signal, of each block and for judging with respect to each block whether or not a motion compensation prediction is performed by using by the motion vector;
a motion compensation predicting means for performing a motion compensation prediction of a reproduced picture signal of a previous frame with respect to each block of which the motion compensation prediction is determined by said motion vector calculating means to be effected and for calculating predicted gray levels of pixels of each block of which the motion compensation prediction is effected;
a prediction error evaluating means for computing the difference between the gray level of each pixel of a coding block of the television picture and the predicted gray level thereof as a prediction error thereof;
a coding method selection means for selecting a method of coding of a block from an intraframe coding and interframe coding methods;
a first switch means for selecting a signal, of which an orthogonal transform is effected, in accordance with the selection made by said coding method selecting means from the gray levels of pixels of blocks represented by the television signal and the prediction errors;
an orthogonal transform means for performing an orthogonal transform of the prediction error or the gray levels selected by said first switch means;
a first quantization step-size computing means for computing a first step size for the quantization from an amount of generated codes;
an average and variance calculating means for calculating an averaged value and a variance of the gray levels of the pixels of each block of input television signal;
a threshold value modifying means for modifying predetermined threshold values according to the first step size to classify blocks, which are represented by luminance signals and are to be coded by effecting the intraframe coding method, into a predetermined number of classes;
a second quantization step-size computing means for classifying the blocks, which are represented by luminance signals and are to be coded by effecting the intraframe coding method, into the predetermined number of classes according to the averaged value and variance and computing a second step size for the quantization of each block from the first step size in case of the blocks to be coded by using an intraframe coding method and for treating the first step sizes as the second step sizes in case of the blocks to be coded by using an interframe coding method;
a quantized transform coefficient calculating means for quantizing coefficients of an orthogonal transform by using the second step size to obtain quantized coefficients of an orthogonal transform;
an orthogonal transform coefficient coding means for performing information on the selection of the coding methods, the coding of the prediction error, the first step size and information on the classes and the quantized coefficients of the orthogonal transform;
an inverse quantization means for effecting an inverse orthogonal transform of the quantized coefficients of the orthogonal transform to obtain inversely-quantized values;
a second switch means for selecting a numerical value of zero or the predicted gray level obtained by the motion compensation prediction as a gray level of a pixels of a reproduced picture according to the selection made by said coding method selection means;
a reproduced picture calculating means for calculating a reproduced picture from the inversely-quantized values and the numerical value of zero or from the predicted gray levels of the pixels of the blocks;
a memory portion for storing the reproduced picture; and
a motion vector coding means for performing the coding of the motion vectors.
11. A motion compensated prediction interframe coding system as set forth in claim 10 wherein the predetermined area is one frame.
12. A motion compensated prediction interframe coding system as set forth in claim 10 wherein the predetermined area is one field.
13. A motion compensated prediction interframe coding system as set forth in claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 or 12 wherein the variance is calculated from the following equation: σ 2 = ( 1 / ( M × N ) ) ∑ i = 1 M ∑ j = 1 N ( p ( i , j ) - P ) 2
where M represents the number of pixels on a row of a block; N the number of rows of the block; p(i,j) a gray level of a pixel at an address (i,j) in the block; and P the averaged value of the gray levels of the pixels of the block obtained by P = ( 1 / ( M × N ) ) ∑ i = 1 M ∑ j = 1 N p ( i , j ) .
14. A motion compensated prediction interframe coding system as set forth in claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 or 12 wherein the variance is calculated from the following equation: D = ( 1 / ( M × N ) ) ∑ i = 1 M ∑ j = 1 N p ( i , j ) - P
where p(i,j) denotes a gray level of a pixel at an address (i,j) in the block; and P the averaged value of the gray levels of the pixels of the block given by P = ( 1 / ( M × N ) ) ∑ i = 1 M ∑ j = 1 N p ( i , j ) .
15. A motion compensated prediction interframe coding system as set forth in claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 or 12 wherein the predetermined number of the classes is four.
16. A motion compensated prediction interframe coding system as set forth in claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 or 12 wherein the second step size is determined to be small for a block having a small variance.
17. A motion compensated prediction interframe coding system as set forth in claim 10 , 11 or 12 wherein the threshold values are modified by using the following equation:
thi=−{thi/(max−thq)}(Qb−thq)+thi
where a subscript i indicates an integer from 1 to 4; and “max” represents a maximum value of the first step size.
18. A moving- image signal encoding apparatus comprising:
a memory portion for storing codes;
means for computing a first step size for quantization from an amount of generated codes or from occupied capacity of the memory portion;
means for modifying the first quantization step size to obtain a second quantization step size; and
means for encoding a signal quantized in accordance with the second quantization step size.
19. A moving- image signal encoding apparatus as set forth in claim 18 , wherein the second quantization step size is computed from the first quantization step size and a local image content.
20. A moving- image signal encoding apparatus as set forth in claim 19 , wherein the local image content is judged from a value of a variance of an input television signal.
21. The moving- image signal encoding apparatus as set forth in claim 19 , wherein the local image content is judged from both of a value of a variance and a value of average which are calculated from an input television signal.
22. A moving- image signal encoding apparatus comprising:
a memory portion for storing codes;
means for computing a first step size for the quantization of a signal from an amount of codes remained in the memory portion;
means for modifying the first quantization step size to obtain a second quantization step size;
means for quantizing the signal in accordance with the second quantization step size; and
means for encoding the quantized signal.
23. The moving- image signal encoding apparatus as set forth in claim 22 , wherein the means for modifying the first quantization size computes the second quantization step size from both of the first quantization step size and a value of a local image characteristic measure which represents local characteristics of an input image represented by an input television signal.
24. The moving- image signal encoding apparatus as set forth in claim 23 , wherein the local image characteristic measure is a variance of the input television signal.
25. The moving- image signal encoding apparatus as set forth in claim 23 , wherein the local image characteristic measure is an average of the input television signal.
26. A method comprising the steps of:
computing a first step size for quantization from an amount of generated codes or from occupied capacity of a memory portion;
modifying the first quantization step size to obtain a second quantization step size; and
encoding a signal quantized in accordance with the second quantization step size.
27. The method as set forth in claim 26 , wherein the step of modifying the first quantization step size comprises the sub- step of computing the second quantization step size from the first quantization step size and a local image content.
28. The method as set forth in claim 27 , wherein the step of modifying the first quantization step size further comprises the sub- step of nudging the local image content from a value of a variance of an input television signal.
29. The method as set forth in claim 27 , wherein the step of modifying the first quantization step size further comprises the sub- step of judging the local image content from both of a value of a variance and a value of average which are calculated from an input television signal.
30. A method comprising the steps of:
computing a first step size for the quantization of a signal from an amount of codes remained in a memory portion;
modifying the first quantization step size to obtain a second quantization step size;
quantizing the signal in accordance with the second quantization step size; and
encoding the quantized signal.
31. The method as set forth in claim 30 , wherein the step of modifying the first quantization step size comprises the sub- step of computing the second quantization step size from both of the first quantization step size and a value of a local image characteristic measure which represents local characteristics of an input image represented by an input television signal.
32. The method as set forth in claim 31 , wherein the local image characteristic measure is a variance of the input television signal.
33. The method as set forth in claim 31 , wherein the local image characteristic measure is an average of the input television signal.Cited by (0)
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