jpcpack.c File Reference

Pack up a data field into a JPEG2000 code stream. More...

#include <stdlib.h>
#include <math.h>
#include "grib2.h"

Go to the source code of this file.

Functions
int	enc_jpeg2000 (unsigned char *, g2int, g2int, g2int, g2int, g2int, g2int, char *, g2int)
	This Function encodes a grayscale image into a JPEG2000 code stream specified in the JPEG2000 Part-1 standard (i.e., ISO/IEC 15444-1) using JasPer Software version 1.500.4 (or 1.700.2) written by the University of British Columbia, Image Power Inc, and others. More...
void	jpcpack (g2float *fld, g2int width, g2int height, g2int *idrstmpl, unsigned char *cpack, g2int *lcpack)
	This subroutine packs up a data field into a JPEG2000 code stream. More...

Detailed Description

Pack up a data field into a JPEG2000 code stream.

Author

Stephen Gilbert

Date

2003-08-17

Definition in file jpcpack.c.

Function Documentation

enc_jpeg2000()

int enc_jpeg2000	(	unsigned char *	cin,
		g2int	width,
		g2int	height,
		g2int	nbits,
		g2int	ltype,
		g2int	ratio,
		g2int	retry,
		char *	outjpc,
		g2int	jpclen
	)

This Function encodes a grayscale image into a JPEG2000 code stream specified in the JPEG2000 Part-1 standard (i.e., ISO/IEC 15444-1) using JasPer Software version 1.500.4 (or 1.700.2) written by the University of British Columbia, Image Power Inc, and others.

JasPer is available at http://www.ece.uvic.ca/~mdadams/jasper/.

Program History Log

Date	Programmer	Comments
2002-12-02	Gilbert	Initial
2004-12-16	Gilbert	Added retry argument allowing increased guard bits.

Parameters

cin	Packed matrix of Grayscale image values to encode.
width	width of image.
height	height of image.
nbits	depth (in bits) of image. i.e number of bits used to hold each data value.
ltype	indicator of lossless or lossy compression. 1, for lossy compression != 1, for lossless compression
ratio	target compression ratio. (ratio:1) Used only when ltype == 1.
retry	If 1 try increasing number of guard bits otherwise, no additional options.
outjpc	Output encoded JPEG2000 code stream.
jpclen	Number of bytes allocated for the output JPEG2000 code stream in outjpc.

Returns

• > 0 = Length in bytes of encoded JPEG2000 code stream
• -3 = Error decode jpeg2000 code stream.
• -5 = decoded image had multiple color components. Only grayscale is expected.

Note

Requires JasPer Software version 1.500.4 or 1.700.2 or later.

Author

Stephen Gilbert

Date

2002-12-02

Definition at line 57 of file enc_jpeg2000.c.

References MAXOPTSSIZE.

Referenced by jpcpack().

jpcpack()

void jpcpack	(	g2float *	fld,
		g2int	width,
		g2int	height,
		g2int *	idrstmpl,
		unsigned char *	cpack,
		g2int *	lcpack
	)

This subroutine packs up a data field into a JPEG2000 code stream.

After the data field is scaled, and the reference value is subtracted out, it is treated as a grayscale image and passed to a JPEG2000 encoder. It also fills in GRIB2 Data Representation Template 5.40 or 5.40000 with the appropriate values.

Program History Log

Date	Programmer	Comments
2003-08-17	Gilbert	Initial.
2004-11-92	Gilbert	Fixed bug packing a near constant field.
2004-07-19	Gilbert	If jpeg2000 encoding fails, try again with different encoder options.
2005-05-10	Gilbert	Imposed minimum size on cpack.

Parameters

fld	Contains the data values to pack.
width	number of points in the x direction.
height	number of points in the y direction.
idrstmpl	Contains the array of values for Data Representation Template Table 5.40 or 5.40000. 0 Reference value - ignored on input, set by jpcpack routine. 1 Binary Scale Factor - used on input, unchanged by jpcpack routine. 2 Decimal Scale Factor - used on input, unchanged by jpcpack routine. 3 number of bits for each data value - ignored on input 4 Original field type - currently ignored on input Data values assumed to be reals. Set to 0 on output. 5 if 0 use lossless compression, if 1 use lossy compression. 6 Desired compression ratio, if idrstmpl[5]=1. Set to 255, if idrstmpl[5]=0.
cpack	The packed data field.
lcpack	Pointer that points to a g2int which contains the length of packed field in cpack. This must be set by the calling function.

Author

Stephen Gilbert

Date

2003-08-17

Definition at line 53 of file jpcpack.c.

References enc_jpeg2000(), int_power(), mkieee(), and sbits().

Referenced by g2_addfield().