SU

Image data stretching utility.

Formats

SU INI name type unit [keywords]
SU MAKE name inlo inhi britlo brithi
SU LIST string
SU TABLE name

Parameters

INI	initializes the stretch table defining the type of calibration, calibration units and initial breakpoint settings; must be used when making a new stretch table
MAKE	enters breakpoints in the table using brightness levels
LIST	lists the saved stretch tables (default=lists all stretch tables on the workstation)
TABLE	lists the breakpoints stored in a stretch table
name	name of the stretch table; eight alphanumeric characters maximum
string	lists the stretch tables beginning with this character string
type	calibration type for the input table (default=any calibration type); to find the calibration type of an image, run IMGLIST FORM=ALL and see the value for type in the output
unit	calibration units for the input table; valid units are RAW, BRIT, RAD, TEMP, ALB or user-defined units; use command IMGPROBE or D to list available units for an image (default=BRIT)
inlo	low value of the breakpoint for input values; specify in units input with the unit parameter (no default)
inhi	high value of the breakpoint for input values; specify in units input with the unit parameter (no default)
britlo	low value of the breakpoint for output brightness values; the range is 0 to 255 (no default)
brithi	high value of the breakpoint for output brightness values; the range is 0 to 255 (no default)

Keywords

BAND=	band number for the input data calibration type (default=all bands)
RANGE=	min max	minimum and maximum values of the input data; these values define the boundary of input values that can later be stretched; see the Remarks

Remarks

Use command SU to make the tables specified with keyword SU in the IMGDISP command. SU sets the tables to stretch raw, radiance, temperature, albedo or brightness values (depending on calibration) to a user-defined brightness value. Then you can use command EU to color the brightness ranges corresponding to the new values.

If you specify keyword RANGE, all input values less than or equal to min are assigned an output value of zero; all input values greater than or equal to max are assigned an output value of 255. Any additional breakpoints specified with the MAKE option that fall outside of min and max are assigned 0 or 255, accordingly. If you don't specify RANGE=, the stretches' slope previous to the first breakpoint is a continuation of the line formed by the first two breakpoints. Likewise, the slope following the last breakpoint is a continuation of the line formed by the last two breakpoints.

Examples

SU LIST

This entry lists all stretch tables saved on the workstation.

SU INI TIRORAD3 TIRO RAD BAND=3

This entry initializes table TIRORAD3 for use on the radiance values of TIROS band 3 images. Each new stretch table must be initialized.

SU MAKE TIRORAD3 0 1.2 20 220

This entry sets the breakpoint values in the above table TIRORAD3. Input 0 corresponds to output 20; input 1.2 corresponds to output 220.

SU TABLE TIRORAD3

This entry lists the breakpoints in table TIRORAD3 and information on BAND, calibration type and units.

SU INI MSATEMP1 MSAT TEMP BAND=1

This entry initializes the table MSATEMP1 to contain breakpoints in temperature for Meteosat band 1 data.

SU MAKE MSATEMP1 240 260 20 240

This entry stretches the temperature values from 240 to 260 in table MSATEMP1, over brightness values 20 to 240.

SU INI GENBRIT X BRIT RANGE=100 200

This entry initializes the table GENBRIT to be used on any calibration type with brightness units. The brightness values from 100 to 200 are stretched to brightness values 0 to 255. Brightness values entered with SU MAKE that are less than 100 or over 200 are assigned 0 or 255, respectively.

SU LIST GEN

This entry lists all the saved stretch tables that begin with GEN.

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