Help for STRETCHF
STRETCHF is a VICAR application program which changes the point by point
intensity of an image by generating a transfer function on the domain of
intensity values. It is similar to the program STRETCH, but is designed to
accept FULLWORD (integer*4) input. Nine types of stretches are available.
These are:
COMP,LINEAR,CONTOUR,ALARM,GAMMA,TABLE,ITABLE,PSTRETCH,FUNCTION
The input image must be fullword. The output image will also be fullword.
The user must specify the DN range of the data by using the DNMIN and DNMAX
parameters.
An optional linear post stretch may be performed following the initial
stretch. This post stretch will take the output image DN values ranging from
DNMIN to DNMAX to a user specified DN range. This post stretch does not require
a separate pass through the data. Instead, the initial stretch and the post
stretch are incorporated in a single look-up table which is then used to process
the input data.
RESTRICTIONS:
1. Only one of the nine types of stretches
available may be specified in a single execution.
2. Input image must be in either fullword format.
3. If a post-stretch is requested the values
specified must be in the range DNMIN to DNMAX.
EXECUTION:
The following is the execution statement for STRETCH:
STRETCH INP OUT PARAMS
where INP, OUT, and PARAMS are parameters discussed in their
respective parameter section in TUTOR mode.
PARAMETERS:
INP
Input dataset
OUT
Output data set
SIZE
Size field = (SL,SS,NL,NS)
SL
Starting line
SS
Starting sample
NL
Number of lines
NS
Number of samples
LINEAR
Linear stretch
supply MIN, MAX
CONTOUR
Contour stretch - needs contour
interval [See DNVALUE]
FUNCTION
User specified function stretch
(Example: FUNC="2*DN+1")
ALARM
Alarm stretch - list DN's to
alarm [See DNVALUE]
GAMMA
Gamma stretch
Supply value of gamma
TABLE
Table stretch
(N Pairs of values -
In, Out,
In, Out,
In, Out,...)
[See BACKGND]
ITABLE
Individual table stretch
(N Pairs of values -
In, Out,
In, Out,
In, Out,...)
[See BACKGND]
POST
Post-stretch option
supply MIN, MAX
OTHER
Other stretch options
Valid: COMP, PSTRETCH
DNVALUE
DN value used for CONTOUR and
ALARM stretches
BACKGND
Background DN value used for
TABLE and ITABLE stretches
FREQ
Frequency for PSTRETCH stretch
AMPL
Amplitude for PSTRETCH stretch
PHI
Phase for PSTRETCH stretch
DC
Mean for PSTRETCH stretch
DNMIN
Minimum DN value
DNMAX
Maximum DN value
See Examples:
Cognizant Programmer: