Bit allocation for sequence image compression
First Claim
1. An image processing system comprising:
- at least one conductor to conduct data to be processed;
local processing circuitry coupled to the at least one conductor to receive and process blocks of the data, to select indices in a compression process to represent each of said blocks of the data and to determine distortion between a first block and a second block of said data, the local processing circuitry being constructed to employ lambda feedback in which distortion associated with at least one previously processed block and the total data size of indices previously selected to represent blocks are used in selecting indices to represent unprocessed blocks; and
output circuitry coupled to the local processing circuitry to output the selected indices.
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Abstract
The invention relates to a method and system for allocating bits for representing blocks that are transmitted in an image compression system. In a preferred embodiment, a video telephone communications system includes a video transmitting/receiving (transceiving) system including local and remote processing systems separated by a communications link. The local processing system determines indices to be sent to a remote processing system to represent the image. Under one aspect of the invention, the local processing system determines an optimal bit allocation in which the following relationship may be minimized DR=D+λR, where D is the total distortion Σdi for a frame; λ is a value determined as described below; R=Σri ≈Rd which is the desired total number of bits for the frame. The optimal bit allocation may determine λ for an entire frame. Under other aspects of the invention a lambda feedback technique, with or without predecision, may be used. The lambda feedback techniques may determine λ block by block. Conditional update preselection and mode preselection are other reduced complexity procedures.
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Citations
25 Claims
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1. An image processing system comprising:
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at least one conductor to conduct data to be processed; local processing circuitry coupled to the at least one conductor to receive and process blocks of the data, to select indices in a compression process to represent each of said blocks of the data and to determine distortion between a first block and a second block of said data, the local processing circuitry being constructed to employ lambda feedback in which distortion associated with at least one previously processed block and the total data size of indices previously selected to represent blocks are used in selecting indices to represent unprocessed blocks; and output circuitry coupled to the local processing circuitry to output the selected indices. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An image processing system comprising:
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local memory storage to store a group of data to be processed; local processing circuitry coupled to the local memory storage to receive blocks of the group of data and to select indices in a compression process to represent the blocks, the local processing circuitry being constructed to select the indices so that DR=D+λ
R is essentially a minimum, where D is a distortion for an unprocessed block of the group of data and R is approximately equal to a desired bit rate for the block, the local processing circuitry also being constructed to select indices to represent an unprocessed block according to a lambda (λ
) determined in accordance with a distortion associated with the most recently processed block and the total data size of indices previously selected to represent blocks; andoutput circuitry coupled to the local processing circuitry to output the selected indices. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An image compression process comprising:
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receiving a plurality of image blocks; and for each block, determining one or more indices suitable for representing said block; calculating a block distortion di and a block bit rate ri associated with each of the one or more indices; determining a lambda λ
for said block in accordance with an actual distortion associated with the block preceding said block through the compression process and the total data size of previously compressed blocks; andselecting an index from among the one or more indices that has the minimum di +λ
ri for said block. - View Dependent Claims (19, 20, 21)
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22. An image compression system comprising:
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circuitry for receiving a plurality of image blocks and, for each block, determining one or more indices suitable for representing said block and calculating a block distortion di and a block bit rate ri associated with each of the one or more indices; circuitry for determining, for each block, a lambda λ
for said block in accordance with an actual distortion associated with the block preceding said block through the compression system and the total data size of previously compressed blocks; andcircuitry coupled to the image block receiving circuitry and the lambda determining circuitry for selecting, for each block, an index from among the one or more indices determined suitable for said block that has the minimum di +λ
ri for said block. - View Dependent Claims (23, 24)
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25. An image processing system comprising:
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circuitry for receiving a plurality of image blocks and, for each block, determining one or more indices suitable for representing said block and calculating a block distortion di and a block bit rate ri associated with each of the one or more indices; circuitry for determining, for each block, a lambda λ
for said block in accordance with an actual distortion associated with the block preceding said block through the compression system and the total data size of previously compressed blocks;circuitry coupled to the image block receiving circuitry and the lambda determining circuitry for selecting, for each block, an index from among the one or more indices determined suitable for said block that has the minimum di +λ
ri for said block;a communications link coupled to the index selecting circuitry for receiving and conducting the selected indices; and decompression circuitry coupled to the communications link for converting the selected indices to image blocks.
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Specification