Raptor code-based image coding method
An image coding and coding technology, applied in the field of image processing, can solve problems such as reducing efficiency, increasing channel occupancy, and fixing, achieving the effects of strict real-time requirements, low complexity, and improved utilization efficiency
Inactive Publication Date: 2012-07-04
XIDIAN UNIV
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Problems solved by technology
The existing channel coding methods have their inherent defects: the code rate of the code is fixed, so the joint source channel coding based on them also has shortcomings: the code rate of the whole system is fixed, and the structure of the code has been changed before the information transmission. OK, cannot generate enough encoded symbols online to decode the original message
When the receiving end cannot correctly decode the original information, the encoded information can only be resent, which will increase the channel occupancy rate and reduce the efficiency
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[0023] refer to figure 1 , the concrete steps of the present invention are as follows:
[0024] Step 1: Perform five-level 9 / 7 wavelet transform on the original image to generate subbands of different frequencies, and interleave the coefficients in the subbands to obtain transformed image coefficients with error tolerance.
[0025] refer to figure 2 , the coefficient interleaving steps in the subband are as follows:
[0026] 1a) Quartering the subbands yields four equal blocks M 1 ,M 2 ,M 3 ,M 4 ,Such as figure 2 as shown in (a);
[0027] 1b) M 1 The block is divided into four equal blocks, and according to the M 1 position, place the four equal blocks intersecting, such as figure 2 as shown in (b);
[0028] 1c) According to the procedure described in 1b), the M 2 ,M 3 ,M 4 Each block is divided into four equal blocks, and according to their positions, the positions of the four equal blocks are intersected.
[0029] Step 2: Quantize the transformed image coef...
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The invention provides a Raptor code-based image coding method, mainly overcoming the defect that in the traditional encoding of the combined signal source and channel, the code rate is fixed so as to enable the channel utilization rate to be low. The realization process comprises the following steps of: 1, carrying out five-stage 9 / 7 wavelet transformation for an original image to produce sub-bands of different frequencies, and interweaving coefficients in the sub-bands; 2, carrying out plane encoding for the sub-bands one by one according to the sequence from low frequency to high frequency, and combining encoded code streams into a plurality of packets corresponding to the sub-bands; 3, carrying out Raptor encoding for the code stream in each packet to obtain the code stream to be transmitted and with corrected code information; 4, transmitting the code streams to be transmitted through a binary deletion channel at the transmitter end, and receiving the transmitted code stream information at the receiver end; and 5, decoding the received code stream information according to the sequence opposite to the sequence at the transmitter end, and finally obtaining a reconstructed image. The invention has the advantage of low complexity, so that the progressive image compression and transmission with strict real-time requirements can be realized.
Description
technical field [0001] The invention belongs to the technical field of image processing, in particular to an image compression method, which can be used for progressive image compression transmission with strict requirements on complexity and real-time performance. Background technique [0002] Image is one of the most important information recording methods at present, especially with the wide application of technologies such as videophone, high-definition television, video conferencing, remote sensing imaging and remote monitoring, images have become the main carrier of information exchange in people's lives. However, when images are transmitted through wireless channels, they are easily disturbed by noise, and the communication quality of images will be greatly reduced. Therefore, the reliable transmission of images in wireless channels has become a current research hotspot. [0003] In recent years, many scholars have proposed a joint source and channel coding scheme, wh...
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Login to View More IPC IPC(8): H04N7/26H04N19/63
Inventor 吴家骥吴信红方勇焦李成
Owner XIDIAN UNIV