NAME

       pngpack.c

SYNOPSIS

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

   Functions
       int enc_png (char *, g2int, g2int, g2int, char *)
           Encode PNG.
       void pngpack (g2float *fld, g2int width, g2int height, g2int *idrstmpl, unsigned char
           *cpack, g2int *lcpack)
           This subroutine packs up a data field into PNG image format.

Detailed Description

       Author
           Stephen Gilbert

       Date
           2003-08-27

       Definition in file pngpack.c.

Function Documentation

   int enc_png (char * data, g2int width, g2int height, g2int nbits, char * pngbuf)
       Encode PNG.

       Parameters
           data data.
           width width.
           height height.
           nbits number of bits.
           pngbuf PNG buffer.

       Returns
           PNG length, or negative number for error.

       Author
           Stephen Gilbert

       Definition at line 81 of file enc_png.c.

       References user_flush_data(), and user_write_data().

       Referenced by pngpack().

   void pngpack (g2float * fld, g2int width, g2int height, g2int * idrstmpl, unsigned char *
       cpack, g2int * lcpack)
       This subroutine packs up a data field into PNG image format. After the data field is
       scaled, and the reference value is subtracted out, it is treated as a grayscale image and
       passed to a PNG encoder. It also fills in GRIB2 Data Representation Template 5.41 or
       5.40010 with the appropriate values.

       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 5.41 or
           5.40010.

           • 0 Reference value - ignored on input, set by pngpack routine.

           • 1 Binary Scale Factor - used on input.

           • 2 Decimal Scale Factor - used on input.

           • 3 number of bits for each grayscale pixel value - ignored on input.

           • 4 Original field type - currently ignored on input, set = 0 on output. Data values
             assumed to be reals.

           cpack The packed data field.
           lcpack length of packed field cpack.

       Author
           Stephen Gilbert

       Date
           2003-08-27

       Definition at line 34 of file pngpack.c.

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

       Referenced by g2_addfield().

Author

       Generated automatically by Doxygen for NCEPLIBS-g2c from the source code.