g2png.F90 File Reference

Pack/unpack a data field into PNG image format, defined in Data Representation Template 5.40. More...

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Functions/Subroutines
subroutine	pngpack (fld, width, height, idrstmpl, cpack, lcpack)
	Pack a data field into PNG image format, defined in [Data Representation Template 5.41](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp5-41.shtml). More...
subroutine	pngunpack (cpack, len, idrstmpl, ndpts, fld)
	Unpack a data field with PNG, defined in [Data Representation Template 5.40](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp5-40.shtml). More...

Detailed Description

Pack/unpack a data field into PNG image format, defined in Data Representation Template 5.40.

Author

Stephen Gilbert

Date

2002-12-21

Definition in file g2png.F90.

Function/Subroutine Documentation

pngpack()

subroutine pngpack	(	real, dimension(width * height), intent(in)	fld,
		integer, intent(in)	width,
		integer, intent(in)	height,
		integer, dimension(*), intent(inout)	idrstmpl,
		character(len = 1), dimension(*), intent(out)	cpack,
		integer, intent(out)	lcpack
	)

Pack a data field into PNG image format, defined in [Data Representation Template 5.41](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp5-41.shtml).

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

[in]	fld	Contains the data values to pack.
[in]	width	number of points in the x direction.
[in]	height	number of points in the y direction.
[in,out]	idrstmpl	Contains the array of values for Data Representation Template 5.2 or 5.3. idrstmpl(1) Reference value - ignored on input. idrstmpl(2) Binary Scale Factor. idrstmpl(3) Decimal Scale Factor. idrstmpl(4) Number of bits containing each grayscale pixel value. idrstmpl(5) Original field type, currently set = 0 on output Data values assumed to be reals. idrstmpl(6) = 0 use lossless compression; = 1 use lossy compression. idrstmpl(7) Desired compression ratio, if idrstmpl(6)=1.
[out]	cpack	The packed data field (character*1 array)
[out]	lcpack	The length of packed field cpack.

Author

Stephen Gilbert

Date

2002-12-21

Definition at line 33 of file g2png.F90.

References enc_png(), g2_sbytesc(), and mkieee().

Referenced by addfield().

pngunpack()

subroutine pngunpack	(	character(len = 1), dimension(len), intent(in)	cpack,
		integer, intent(in)	len,
		integer, dimension(*), intent(in)	idrstmpl,
		integer, intent(in)	ndpts,
		real, dimension(ndpts), intent(out)	fld
	)

Unpack a data field with PNG, defined in [Data Representation Template 5.40](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp5-40.shtml).

This subroutine unpacks a data field that was packed into a PNG image format using info from the GRIB2 Data Representation Template 5.40 or 5.40000.

Parameters

[in]	cpack	The packed data field (character*1 array).
[in]	len	length of packed field cpack().
[in]	idrstmpl	Contains the array of values for Data Representation Template 5.40 or 5.40000.
[in]	ndpts	The number of data values to unpack.
[out]	fld	Contains the unpacked data values.

Author

Stephen Gilbert

Date

2000-06-21

Definition at line 167 of file g2png.F90.

References dec_png(), g2_gbytesc(), and rdieee().

Referenced by getfield(), and gf_unpack7().