Error resilient still image packetization method and packet structure
First Claim
1. A method of encoding a still image which improves the error resiliency of the resulting bitstream, comprising the steps of:
- decomposing a still image with a wavelet transform, choosing a scanning method with which to scan the wavelet coefficients produced by said decomposition, scanning the wavelet coefficients of a texture unit which is defined in accordance with said chosen scanning method, coding the wavelet coefficients of said texture unit to produce a bitstream, adding said bitstream to a packet which includes a data stream, all of the bits of the bitstream resulting from said coding of said texture unit becoming part of said packet'"'"'s data stream, determining, in accordance with a first predetermined criterion, whether the packet associated with said data stream should be closed, repeating the steps of scanning and coding the wavelet coefficients of a texture unit to produce a bitstream and adding the resulting bitstream to said data stream for additional texture units until said first predetermined criterion for closing said packet has been met, constructing a packet header for said data stream, said packet header comprising;
a resynchronization marker for enabling a decoder to resynchronize with the encoder producing said bitstream if synchronization is lost, and at least one index number, each of said index numbers identifying a respective one of the texture units in the packet header'"'"'s associated data stream, for enabling a decoder to associate following packets with their correct position in the wavelet transform domain, and combining said packet header and its associated data stream to form a packet suitable for transmitting over a communication channel, the use of said encoding method providing independently decodable packets and thereby improving the error resilience of said bitstream by eliminating dependencies across the packets and isolating corrupted data to a single packet.
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Abstract
A packetization method and packet structure improve the robustness of a bitstream generated when a still image is decomposed with a wavelet transform. The wavelet coefficients of one “texture unit” are scanned and coded in accordance with a chosen scanning method to produce a bitstream. The bitstreams for an integral number of texture units are assembled into a packet, each of which includes a packet header. Each packet header includes a resynchronization marker to enable a decoder to resynchronize with the bitstream if synchronization is lost, and an index number which absolutely identifies one of the texture units in the packet to enable a decoder to associate following packets with their correct position in the wavelet transform domain. The header information enables a channel error to be localized to a particular packet, preventing the effects of the error from propagating beyond packet boundaries. The invention is applicable to the pending MPEG-4 and JPEG-2000 image compression standards.
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Citations
29 Claims
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1. A method of encoding a still image which improves the error resiliency of the resulting bitstream, comprising the steps of:
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decomposing a still image with a wavelet transform, choosing a scanning method with which to scan the wavelet coefficients produced by said decomposition, scanning the wavelet coefficients of a texture unit which is defined in accordance with said chosen scanning method, coding the wavelet coefficients of said texture unit to produce a bitstream, adding said bitstream to a packet which includes a data stream, all of the bits of the bitstream resulting from said coding of said texture unit becoming part of said packet'"'"'s data stream, determining, in accordance with a first predetermined criterion, whether the packet associated with said data stream should be closed, repeating the steps of scanning and coding the wavelet coefficients of a texture unit to produce a bitstream and adding the resulting bitstream to said data stream for additional texture units until said first predetermined criterion for closing said packet has been met, constructing a packet header for said data stream, said packet header comprising;
a resynchronization marker for enabling a decoder to resynchronize with the encoder producing said bitstream if synchronization is lost, and at least one index number, each of said index numbers identifying a respective one of the texture units in the packet header'"'"'s associated data stream, for enabling a decoder to associate following packets with their correct position in the wavelet transform domain, and combining said packet header and its associated data stream to form a packet suitable for transmitting over a communication channel, the use of said encoding method providing independently decodable packets and thereby improving the error resilience of said bitstream by eliminating dependencies across the packets and isolating corrupted data to a single packet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A packet structure suitable for use when transmitting a bitstream produced by encoding a still image, comprising:
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a data stream, said data stream comprising at least one texture unit, each of said texture units comprising a respective bitstream generated by scanning and coding the wavelet coefficients produced by a wavelet decomposition of a still image in accordance with a predetermined scanning method, and a packet header, said packet header including;
a resynchronization marker for resynchronizing a decoder to the encoder which produces said bitstream if synchronization is lost, and an index number which absolutely identifies one of said texture units in said data stream for enabling a decoder to associate following packets with their correct position in the wavelet transform domain, said packet header and said data stream combined to form a packet suitable for conveying a bitstream representing at least a portion of a still image across a communication channel. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification