wpc.comp.dwpt.2d.lib

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WPC - routines for compress a 2D seismic section using wavelet packets 

wpcCompress	compress a 2D section
wpcUncompress	uncompress and generate a 2D section
wpcN1		obtain the # of samples in the fast dimension
wpcN2		obtain the # of samples in the slow dimension
wpcSize		length of the compressed bit stream
wpcFree		free up the space for the compressed data
wpcWrite	write the compressed data to a file
wpcRead		read compressed data from a file 
Function Prototypes:

void *wpcCompress(float *f, int n1, int n2, float error, int *nbytes);
int wpcUncompress(void *w, float *f);
int wpcN1(void *wpc);
int wpcN2(void *wpc);
int wpcSize(void *wpc);
void wpcFree(void *wpc);


wpcCompress:
Input:
f	pointer to the 2D section
n1	# of samples in the fast dimension
n2	# of samples in the slow dimension
error	relative RMS error tolerable during compression
Output:
nbytes	# of bytes after compression 
Return:	pointer to the compressed data

wpcUncompress:
Input:
w	pointer to the compressed data
Output:
f	pointer to the uncompress 2D section
Return:	consistency flag, 1 if wpcCompressed data, 0 otherwise

wpcN1:
Input:
wpc	pointer to the compressed data
Return:	# of samples in the fast dimension	

wpcN2:
Input:
wpc	pointer to the compressed data
Return:	# of samples in the slow dimension	

wpcSize:
Input:
wpc	pointer to the compressed data
Return:	# of bytes after compression

wpcFree:
Input:
wpc	pointer to the compressed data

wpcWrite:
Input:
wpc	pointer to the compressed data
fp	file pointer to which to write

wpcRead:
Input:
fp	file pointer to which to write

Return:	pointer to the compressed data

wpcCompress:
Notes:
The compression is done block by block, so the data is tiled first.
The size of the tiling is set in the routine wpcInitConfig. 
Those numbers are obtained empirically. To support upgrading, 
the numbers and the filter parameters are stored as the header.	
Since we cannot determine the size of the output before compression,
memory is allocated within this routine, and adjusted after the
compression.  
Author:		Tong Chen, 07/27/94