Method and apparatus for digital data compression

Abstract

The quality of digital images recovered from compressed data in an inter-frame redundancy-removing scheme is enhanced using a self-adaptive feedback scheme in an image compression/decompression system so as to include means for the compensation of the distortion component from prior frame compression in subsequent difference frame compression. Each transmitted frame is stored after a full compress/decompress cycle, and difference data (which includes the inverse of the distortion component from compression of the transmitted frame) representing the difference between the stored frame and the incoming new frame is transmitted. Consequently, the quality of static regions in the recovered images may be improved with each subsequent iteration by taking the distortion component in the prior frame into consideration along with the inter-frame motion information. The feedback loop thus forms a self-adaptive iterative cycle.

What is claimed is:  
     
         1 . A method, comprising: 
 storing first image frame data representing a first frame of a video image sequence;    subtracting the first image frame data from second image frame data representing a next frame of the video image sequence to produce difference data; and    updating the first image frame data with the difference data.    
     
     
         2 . The method of  claim 1  further comprising transmitting the difference data.  
     
     
         3 . The method of  claim 1  further comprising transforming the first image frame data from a first format to a second format prior to storing the first image frame data.  
     
     
         4 . The method of  claim 3  wherein the first image frame data is stored in the first format during the step of storing.  
     
     
         5 . The method of  claim 4  further comprising compressing the first image frame data prior to storing the first image frame data.  
     
     
         6 . The method of  claim 5  wherein the first image frame data is compressed following the step of transforming.  
     
     
         7 . The method of  claim 6  further comprising decompressing the first image frame data prior to storing the first image frame data.  
     
     
         8 . The method of  claim 7  wherein the second format comprises a wavelet representation.  
     
     
         9 . The method of  claim 2  further comprising encoding the difference data prior to the step of transmitting.  
     
     
         10 . A method comprising: 
 transmitting preceding frame data through a transmission channel;    subtracting the preceding frame data from subsequent frame data to produce difference data; and    transmitting the difference data.    
     
     
         11 . The method of  claim 10  further comprising storing the preceding frame data prior to the subtracting.  
     
     
         12 . The method of  claim 11  further comprising updating the stored preceding frame data with the difference data.  
     
     
         13 . The method of  claim 10  further comprising reconstructing the subsequent frame data from the preceding frame data and the difference data.  
     
     
         14 . A method comprising the steps of: 
 transmitting preceding frame data through a transmission channel having a limited transmission bandwidth;    feeding back transmitted preceding frame data to a current frame; and    updating the transmitted preceding frame with difference data representing the difference between the transmitted preceding frame and the current frame.    
     
     
         15 . The method of  claim 14  wherein updating the transmitted preceding frame comprises transmitting the difference data through the transmission channel.  
     
     
         16 . The method of  claim 14  wherein updating the transmitted preceding frame further comprises combining the transmitted preceding frame with the difference data to reconstruct the current frame.  
     
     
         17 . The method of  claim 14  further comprising the steps of: 
 receiving the transmitted preceding frame;  
 receiving the transmitted difference data;  
 reconstructing the current frame based on the transmitted preceding frame and the transmitted difference data.  
 
     
     
         18 . The method of  claim 14  further comprising the step of compressing the preceding frame.  
     
     
         19 . The method of  claim 16 , wherein the difference data includes data representing inter-frame differences between the preceding frame and the current frame as well as information representing a distortion component arising from data compression of the preceding frame.  
     
     
         20 . The method of  claim 19 , wherein the data compression comprises quantization and the distortion component comprises quantization losses.  
     
     
         21 . The method of  claim 20 , wherein the transmitted preceding frame comprises quantized data and the difference data represents the difference between data representing the current frame and data obtained by dequantizing the quantized data in the transmitted preceding frame.  
     
     
         22 . The method of  claim 20 , wherein the transmitted preceding frame comprises compressed data and the difference data represents the difference between data representing the current frame and data obtained by decompressing the compressed data in the transmitted preceding frame.  
     
     
         23 . The method of  claim 20 , further comprising compressing the difference data prior to transmission.  
     
     
         24 . The method of  claim 19 , wherein the preceding frame comprises video images.  
     
     
         25 . The method of  claim 19 , wherein the preceding frame comprises temporal coherent images.  
     
     
         26 . The method of  claim 19 , wherein the preceding frame comprises natural images and/or synthetic images.  
     
     
         27 . The method of  claim 14  further comprising the step of storing data representing the transmitted preceding frame in an accumulation buffer.  
     
     
         28 . The method of  claim 27 , wherein the data stored in the accumulation buffer is deserved from the data in the transmitted preceding frame.  
     
     
         29 . The method of  claim 27 , further comprising the step of updating the data stored in the accumulation buffer with the transmitted difference data to obtain data representing the current frame.  
     
     
         30 . The method of  claim 29 , wherein the difference data used to update the data stored in the accumulation buffer is decompressed from data in the transmitted difference data.  
     
     
         31 . The method of  claim 27  further comprising the step of determining whether the current frame is a key frame or a difference frame, wherein in the event a key frame is encountered, the difference data represents the entire current frame.  
     
     
         32 . The method of  claim 31  wherein in the event the current frame is a difference frame, the difference data is added to the data stored in the accumulation buffer, and in the event the current frame is a key frame, the difference data replaces the data stored in the accumulation buffer.  
     
     
         33 . The method of  claim 14  further comprising the step of transforming the preceding frame into a wavelet domain before it is transmitted.  
     
     
         34 . The method of  claim 33  further comprising the step of transforming the current frame into the wavelet domain before obtaining the difference data.  
     
     
         35 . The method of  claim 34  wherein the transmitted preceding frame is subject to data compression by quantization of the data blocks.  
     
     
         36 . The method of  claim 35  wherein the extent of quantization is relatively less for higher resolution blocks compared to lower resolution blocks.  
     
     
         37 . The method of  claim 36  wherein the transmitted preceding frame and difference data are transmitted to a receiving device, comprising one of a decompaction device, a storage device or a remote transmission device.  
     
     
         38 . A method comprising the steps of: 
 compressing a first merge frame and transmitting the first merge frame in compressed format;    obtaining difference data that represents difference between a second merge frame and data representing the transmitted first merge frame; and    applying the difference data to the transmitted first frame for reconstructing a transmitted second frame.    
     
     
         39 . A method comprising the steps of: 
 (a) applying an incoming frame as a target frame;    (b) compacting the target frame to obtain a compacted target frame;    (c) determine whether a next incoming frame is a difference frame or a key frame;    (d) if the next incoming frame is a difference frame, comparing said incoming frame with the compacted target frame to obtain a difference data frame to be applied as a next target frame;    (e) repeating steps (b) to (d) for a desired number of incoming frames or until a key frame is encountered.    
     
     
         40 . A method as in  claim 39  further comprising the step of storing the compacted target frame prior to step (c).  
     
     
         41 . A method as in  claim 39  further comprising the step of decompacting the compacted target frame to obtain a decompacted target frame prior to step (c).  
     
     
         42 . A method as in  claim 41  further comprising the step of storing the decompacted target frame.  
     
     
         43 . A method as in  claim 39  further comprising the steps of: 
 (h) if the next incoming frame is a key frame, applying the next incoming frame as the next target frame; and  
 (i) repeating steps (b) to (h) for the desired number of incoming frames.  
 
     
     
         44 . A method as in  claim 39  further comprising the step of transforming each incoming frame into a wavelet domain before applying the incoming frames as target frames, wherein data in each incoming frame in the wavelet domain has been filtered into data blocks, each data block representing a certain resolution of the corresponding incoming frame.  
     
     
         45 . A method as in  claim 44  wherein the next incoming frame and the compacted target frame are compared by comparison in the wavelet domain.  
     
     
         46 . A method as in  claim 45  wherein the target frame is compacted by quantization of its data blocks.  
     
     
         47 . A method as in  claim 46  wherein the extent of quantization is relatively less for higher resolution data blocks of the incoming frames compared to lower resolution data blocks thereof.  
     
     
         48 . A method as in  claim 39  wherein in step (c), the next incoming frame is determined to be a difference frame or a key frame by comparing an energy signature of the next incoming frame to an energy signature of a preceding incoming frame.  
     
     
         49 . A method as in  claim 48  wherein the energy signature of the next incoming frame is represented by a lowest resolution data block in a wavelet domain.  
     
     
         50 . A method as in  claim 39  wherein the compaction step (b) comprises an implied quantization scheme.  
     
     
         51 . A method as in  claim 50  wherein each incoming frame comprises data arranged in bit planes in a number of data blocks within a wavelet domain, and the implied quantization scheme comprises the step of allocating a number of such bit planes to be retained for each data block within the wavelet domain.  
     
     
         52 . A method as in  claim 51  wherein the allocating step comprises allocating a larger number of the bit planes for data blocks of higher resolution and a lesser number of the bit planes for data blocks of lower resolution.  
     
     
         53 . A method as in  claim 52  wherein the implied quantization scheme allocates the number of bit planes to be retained for data transmission and/or data storage.  
     
     
         54 . A method as in  claim 39  further comprising the step of transforming an incoming sequence of image frames represented in true color components into luminance and chrominance components, wherein the transforming step comprises the steps of: 
 reducing the number of bits used to represent one or more of the true color components; and  
 prior to such bit size reduction, augmenting the value of the one or more true color components by a predetermined fraction of an increment of the expected bit representation after the bit size reduction.  
 
     
     
         55 . A method as in  claim 54  wherein the predetermined fraction is one-half of the increment.  
     
     
         56 . A method as in  claim 39  further comprising the steps of: 
 reducing the number of bits used to represent data of each incoming frame;  
 prior to such bit size reduction, augmenting the value of the data by a predetermined fraction of an increment of the expected bit representation after the bit size reduction.  
 
     
     
         57 . A method as in  claim 56  wherein the predetermined fraction is one-half of the increment.  
     
     
         58 . A method as in  claim 39  further comprising the step of reconstructing one or more of the incoming frames from a number of allocated bit planes thereof, wherein the reconstructing step comprises augmenting each value indicated by the allocated bit planes of each corresponding incoming frame by an amount between that value and a next possible higher binary value that can be represented by the allocated bit planes of the corresponding incoming frame.  
     
     
         59 . A method as in  claim 58  wherein each value is augmented to an average between said indicated value and said next possible higher binary value.  
     
     
         60 . A method as in  claim 58  wherein each value is augmented to be between a first value represented by the bits of the allocated bit planes of the corresponding incoming frame along with non-retained lower significant bits being one and a second value represented by the bits of the allocated bit planes of the corresponding incoming frame along with non-retained lower significant bits being zero.  
     
     
         61 . A method as in  claim 60  wherein each value is augmented to an average between the first and second values.  
     
     
         62 . A method as in  claim 39  further comprising truncating lower significant bits of data of each incoming frame so us to retain only higher significant bits thereof, and reconstructing the data by augmenting each value represented by the data to be between a first value represented by the higher significant bits along with non-retained lower significant bits being one and a second value represented by higher significant bits along with non-retained lower significant bits being zero.  
     
     
         63 . A method as in  claim 62  wherein each value is augmented to an average between the first and second values.  
     
     
         64 . A method as in  claim 39  wherein the incoming frames comprise digital video frames.  
     
     
         65 . A method of reconstructing image frames based on compacted data transmitted from a source, comprising the steps of: 
 receiving first frame data representing a first frame that has been compacted;    receiving difference data representing a difference between a second frame and the compacted first frame; and    applying the difference data to the first frame data to reconstruct the second frame.    
     
     
         66 . A system for compacting image frames for transmission through limited transmission bandwidth with reduced distortion, comprising: 
 means for transmitting preceding frame data through the limited transmission bandwidth;    means for feeding back transmitted preceding frame data to a current frame; and    means for updating the transmitted preceding frame with difference data representing the difference.    
     
     
         67 . A method comprising: 
 allocating a predetermined number of higher significant bits to be retained for each of a number of digital data samples; and    discarding non-retained lower significant bits of the digital data samples for further data handling.    
     
     
         68 . A method as in  claim 67  wherein the digital data samples represent data of different resolutions.  
     
     
         69 . A method as in  claim 68  wherein allocating comprises allocating a larger number of higher significant bits for those of the digital data samples that represent data of higher resolution and allocating a lesser number of higher significant bits for those of the digital data samples that represent data of lower resolution.  
     
     
         70 . A method as in  claim 67  further comprising the step of reconstructing the digital data samples from the bits allocated by augmenting each value indicated by the allocated bits of each corresponding sample by an amount between that indicated value and a next possible higher binary value that can be represented by the allocated bits of the corresponding sample.  
     
     
         71 . A method as in  claim 70  wherein each value is augmented to be between a first value represented by the allocated bits of a corresponding sample along with the non-retained lower significant bits of that sample being one, and a second value represented by the allocated bits of the corresponding sample along with the non-retained lower significant bits of that sample being zero.  
     
     
         72 . A method as in  claim 67  wherein the samples are represented by bit planes, ranging from bit planes comprising higher significant bits to bit planes comprising lower significant bits, and wherein a predetermined number of bit planes of higher significant bits are allocated to be retained and non-retained bit planes of lower significant bits are treated as zeros and discarded for further data handling.  
     
     
         73 . A method as in  claim 72  wherein the bit planes define a frame of samples.  
     
     
         74 . A method as in  claim 73  wherein the samples are represented in a wavelet domain, and wherein the digital data of the samples has been filtered into data blocks, each data block representing a certain resolution of a corresponding frame.  
     
     
         75 . A method as in  claim 74  wherein the allocating step allocates a predetermined number of bit planes to be retained for each corresponding data block within the wavelet domain.  
     
     
         76 . A method as in  claim 75  wherein the predetermined number of bit planes for each corresponding data block varies, depending on the resolution of the corresponding data block.  
     
     
         77 . A method as in  claim 76  wherein a larger number of bit planes are allocated for corresponding data blocks of higher resolution and a lesser number of bit planes are allocated for corresponding data blocks of lower resolution.  
     
     
         78 . A method as in  claim 77  further comprising the step of reconstructing frames from the allocated bit planes by augmenting each value indicated by the allocated bit planes of a corresponding data block by an amount between that value and a next possible higher binary value that can be represented by the allocated bit planes of that corresponding data block.  
     
     
         79 . A method as in  claim 78  wherein each value is augmented to an average between the indicated value and the next possible higher binary value.  
     
     
         80 . A method as in  claim 78  wherein each value is augmented to be between a first value represented by the bits of the allocated bit planes along with non-retained lower significant bits being one and a second value represented by the bits of the allocated bit planes along with non-retained lower significant bits being zero.  
     
     
         81 . A method as in  claim 80  wherein each value is augmented to an average between the first and second values.  
     
     
         82 . A method as in  claim 67  further comprising transmitting the allocated bits across a limited transmission bandwidth channel.  
     
     
         83 . A method as in  claim 67  further comprising storing the allocated bits in a limited storage bandwidth device.  
     
     
         84 . A method for reconstructing digital data, comprising augmenting each value representing the data to be between a first value represented by a number of retained higher significant bits of the data along with a number of non-retained lower significant bits of the data being one, and a second value represented by the number of retained higher significant bits of the data along with the number of non-retained lower significant bits being zero.  
     
     
         85 . A method as in  claim 84  wherein each value is augmented to an average between said first and second values.  
     
     
         86 . A method as in  claim 84  wherein the digital data values are represented in bit planes ranging from bit planes comprising higher significant bits to bit planes comprising lower significant bits, wherein the bit planes of lower significant bits are truncated and the bit planes of higher significant bits are retained, and wherein each digital data value is augmented to be between a first value represented by the bits of the retained bit planes along with non-retained lower significant bits being one and a second value represented by the bits of the retained bit planes along with non-retained lower significant bits being zero.  
     
     
         87 . A method as in  claim 86  wherein each value is augmented to an average between the first and second values.  
     
     
         88 . A method for improving the accuracy of binary data values that are subject to bit size reduction, comprising the step of augmenting the values of the binary data prior to the bit size reduction by a predetermined fraction of an increment of the expected bit representation after bit size reduction, so as to improve the accuracy of the binary data values upon reconstruction.  
     
     
         89 . A method as in  claim 88  wherein the predetermined fraction is one-half of the increment.  
     
     
         90 . A method comprising: 
 obtaining difference data that represents a difference between data representing a current frame and data representing a transmitted preceding frame; and    transmitting the difference data, wherein the difference data is to be applied for reconstructing a transmitted current frame.    
     
     
         91 . A method as in  claim 90 , wherein the preceding frame is subject to data compaction prior to transmission.  
     
     
         92 . A method as in  claim 91 , wherein the data compaction comprises quantization and the preceding frame includes a distortion component comprising quantization losses.  
     
     
         93 . A method as in  claim 92 , wherein the difference data includes data representing inter-frame differences between the preceding frame and the current frame as well as information representing a distortion component arising from data compaction of the preceding frame.  
     
     
         94 . A method as in  claim 91 , further comprising the step of compacting the difference data prior to transmission.  
     
     
         95 . A method as in  claim 90 , wherein the transmitted preceding frame comprises quantized data and the difference data represents the difference between data representing the current frame and data obtained by dequantizing the quantized data in the transmitted preceding frame.  
     
     
         96 . A method as in  claim 90 , wherein the transmitted preceding frame comprises compressed data and the difference data represents the difference between data representing the current frame and data obtained by decompressing the compressed data in the transmitted preceding frame.  
     
     
         97 . A method as in  claim 90  further comprising the step of storing data representing the transmitted preceding frame in an accumulation buffer.  
     
     
         98 . A method as in  claim 97 , wherein the data stored in the accumulation buffer is data decompacted from data compacted in the transmitted preceding frame.  
     
     
         99 . A method as in  claim 97 , further comprising the step of updating the data stored in the accumulation buffer with the transmitted difference data to obtain data representing the current frame.  
     
     
         100 . A method as in  claim 99 , wherein the difference data used to update the data stored in the accumulation buffer is decompacted from data compacted in the transmitted difference data.  
     
     
         101 . A method as in  claim 90  further comprising the step of determining whether the current frame is a key frame or a difference frame, wherein in the event a key frame is encountered, the difference data represents the entire current frame.  
     
     
         102 . A method as in  claim 101  wherein in the event the current frame is a difference frame, the difference data is added to the data stored in the accumulation buffer, and in the event the current frame is a key frame, the difference data replaces the data stored in the accumulation buffer.  
     
     
         103 . A method as in  claim 90  further comprising the step of transforming the data representing the preceding frame from a spatial domain into a wavelet domain before transmitting the preceding frame, wherein the data in the wavelet domain has been filtered into data blocks, each representing a certain resolution of the preceding frame.  
     
     
         104 . A method as in  claim 103  further comprising the step of transforming the data representing the current frame from the spatial domain into the wavelet domain before obtaining the difference data, wherein the difference data is obtained by comparison between the current frame and transmitted preceding frame in the wavelet domain.  
     
     
         105 . A method as in  claim 104  wherein the transmitted preceding frame is subject to data compaction by quantization of the data blocks.  
     
     
         106 . A method as in  claim 105  wherein relatively less quantization is applied for higher resolution data blocks compared to lower resolution data blocks.  
     
     
         107 . A method as in  claim 106  wherein the transmitted preceding frame and difference data are transmitted to a receiving device comprising one of a decompaction device, a storage device, or a remote transmission device.  
     
     
         108 . A method as in  claim 105  wherein the data representing the preceding frame and the data representing the current frame are subject to an implied quantization scheme in the wavelet domain.  
     
     
         109 . A method as in  claim 108  wherein each frame comprises data arranged in bit planes in each block within the wavelet domain, and the implied quantization scheme comprises the step of allocating the number of bit planes to be retained for each data block within the wavelet domain.  
     
     
         110 . A method as in  claim 109  wherein the allocating step comprises the step of allocating a larger number of bit planes for data blocks of higher resolution and a lesser number of bit planes for data blocks of lower resolution.  
     
     
         111 . A method as in  claim 110  wherein the implied quantization scheme allocates the number of bit planes to be retained for data transmission or data storage.  
     
     
         112 . A method as in  claim 90  further comprising the step of transforming the data representing the current frame from true color components into luminance and chrominance components wherein the transforming comprises: 
 reducing the number of bits representing one or more of the true color components:  
 prior to such bit reduction, augmenting the value represented by the bits of the one or more true color components by a predetermined fraction of an increment of the expected bit representation after the bit size reduction.  
 
     
     
         113 . A method as in  claim 112  wherein the predetermined fraction is one-half of the increment.  
     
     
         114 . A method as in  claim 90  further comprising the steps of: 
 reducing the number of bits representing each data value of each frame;  
 prior to such bit size reduction, augmenting the value represented by the bits of each data value by a predetermined fraction of an increment of the expected bit representation after the bit size reduction.  
 
     
     
         115 . A method as in  claim 114  wherein the predetermined fraction is one-half of the increment.  
     
     
         116 . A method as in  claim 90  further comprising the step of reconstructing the transmitted current frame from a number of allocated bit planes by augmenting each value indicated by the allocated bit planes by an amount between the indicated value and a next possible higher binary value that can be represented by the allocated bit planes.  
     
     
         117 . A method as in  claim 116  wherein each value is augmented to an average between the indicated value and the next possible higher binary value.  
     
     
         118 . A method as in  claim 116  wherein each value is augmented to be between a first value represented by the bits of the allocated bit planes along with non-retained lower significant bits being one and a second value represented by the bits of the allocated bit planes along with non-retained lower significant bits being zero.  
     
     
         119 . A method as in  claim 118  wherein each value is augmented to an average between the first and second values.  
     
     
         120 . A method as in  claim 90  further comprising the steps of truncating lower significant bits of the data representing the current frame so as to retain only higher significant bits, and reconstructing the data of the transmitted current frame by augmenting each value represented by that data to be between a first value represented by the higher significant bits along with non-retained lower significant bits being one and a second value represented by the higher significant bits along with the non-retained lower significant bits being zero.  
     
     
         121 . A method as in  claim 120  wherein each value is augmented to an average between the first and second values.  
     
     
         122 . A method as in  claim 90  wherein the current and preceding frames are digital video frames.  
     
     
         123 . A method as in  claim 90 , wherein the current and preceding frames include video images.  
     
     
         124 . A method as in  claim 90 , wherein the current and preceding frames include temporal coherent images.  
     
     
         125 . A method as in  claim 90 , wherein the current and preceding frames include natural images and/or synthetic images.  
     
     
         126 . A system for handling image frames through limited bandwidth with reduced distortions comprising: 
 comparison means for obtaining difference data that represents a difference between data representing a current frame and data representing a compacted preceding frame;    means for transmitting the difference data; and    means for applying the difference data to reconstruct a transmitted current frame.    
     
     
         127 . A method for compacting a sequence of image frames that are represented in spatial domain comprising: 
 transforming each frame into wavelet domain, wherein each wavelet domain frame is filtered into data blocks, each data block including data representing a certain resolution of the frame; and    quantizing the data in each data block.    
     
     
         128 . A method as in  claim 127 , wherein the data in each of the data blocks is quantized to a different extent depending on the resolution of the respective data block.  
     
     
         129 . A method as in  claim 128 , wherein the data in data blocks representing higher resolution blocks is quantized to a relatively lesser extent and the data in data blocks representing lower resolution blocks is quantized to a relatively higher extent.  
     
     
         130 . A method as in  claim 129  further comprising the step of comparing a transmitted preceding frame and a current frame in the wavelet domain to obtain a difference data that is to be applied to reconstruct a transmitted current frame based on the transmitted preceding frame.  
     
     
         131 . A method as in  claim 130  further comprising the step of determining whether the current frame is a difference frame or a key frame prior to obtaining the difference data.  
     
     
         132 . A method as in  claim 131  wherein the current frame is determined to be a difference frame or a key frame by comparing an energy signature of the current frame to an energy signature of the preceding frame.  
     
     
         133 . A method as in  claim 132  wherein the energy signature of the current frame is represented by a lowest resolution data block in the wavelet domain.  
     
     
         134 . A method as in  claim 127  wherein the image frames in the wavelet domain are subjected to an implied quantization scheme.  
     
     
         135 . A method as in  claim 134  wherein each frame comprises data arranged in bit planes in each data block within the wavelet domain, and the implied quantization scheme comprises the step of allocating the number of bit planes to be retained for each data block within the wavelet domain.  
     
     
         136 . A method as in  claim 135  wherein the allocating step comprises the step of allocating a larger number of bit planes for data blocks of higher resolution and a lesser number of bit planes for data blocks of lower resolution.  
     
     
         137 . A method as in  claim 136  wherein the implied quantization scheme allocates the number of bit planes to be retained for data transmission.  
     
     
         138 . A method as in  claim 137  wherein the implied quantization scheme allocates the number of bit planes to be retained for data storage.  
     
     
         139 . A method as in  claim 127  further comprising the step of transforming the sequence of image frames represented in true color components into luminance and chrominance components, wherein transforming comprises: 
 reducing the number of bits used to represent one or more of the true color components; and  
 prior to such bit reduction, augmenting the value of the one or more true color components by a predetermined fraction of an increment of the expected bit representation after the bit size reduction.  
 
     
     
         140 . A method as in  claim 139  wherein the predetermined fraction is one-half of the increment.  
     
     
         141 . A method as in  claim 127  further comprising the steps of: 
 reducing the bit size of values representing data of each frame;  
 prior to the bit size reduction, augmenting the values of the data by a predetermined fraction of an increment of the expected bit representation after the bit size reduction.  
 
     
     
         142 . A method as in  claim 141  wherein the predetermined fraction is one-half of the increment.  
     
     
         143 . A method as in  claim 127  further comprising the step of reconstructing the frames from a number of allocated bit planes by augmenting each value indicated by the allocated bit planes by an amount between said indicated value and the next possible higher binary value that can be represented by the allocated bit planes.  
     
     
         144 . A method as in  claim 143  wherein each value is augmented to an average between said indicated value and said next possible higher binary value.  
     
     
         145 . A method as in  claim 143  wherein each value is augmented to be between a first value represented by the bits of the allocated bit planes along with non-retained lower significant bits being one and a second value represented by the bits of the allocated bit planes along with non-retained lower significant bits being zero.  
     
     
         146 . A method as in  claim 145  wherein each value is augmented to an average between the first and second values.  
     
     
         147 . A method as in  claim 127  further comprising the steps of truncating lower significant bits of data values of each frame so as to retain only higher significant bits thereof, and reconstructing the frames by augmenting data values so truncated to be between a first value represented by the higher significant bits along with non-retained lower significant bits being one and a second value represented by the higher significant bits along with non-retained lower significant bits being zero.  
     
     
         148 . A method as in  claim 147  wherein each data value is augmented to an average between the first and second values.  
     
     
         149 . A method as in  claim 127  wherein the frames comprise digital video frames.  
     
     
         150 . A method as in  claim 149  wherein the digital video frames comprise synthetic and/or natural images.  
     
     
         151 . In a system for compaction of image frames that are in a spatial domain, which is structured and configured to update a transmitted preceding frame that underwent compaction using inter-frame differences between a current frame and the preceding frame, an improvement for reducing distortions comprising: 
 transformation means for transforming the frames into a wavelet domain; and    means for quantizing the data in the wavelet domain.    
     
     
         152 . The improvement of  claim 151  wherein the data in the wavelet domain is selectively quantized depending on the current frame resolution represented by the data.  
     
     
         153 . The improvement of  claim 152  further comprising comparison means for obtaining difference data that represents a difference between data representing the current frame and data representing the compacted preceding frame; wherein the difference data is to be applied for reconstructing a transmitted current frame based on the transmitted preceding frame.