AIPS HELP file for SCLIM in 31DEC24
As of Fri Apr 19 1:13:50 2024
SCLIM: Task to operate on an image with mathematical functions
INPUTS
INNAME Input image name
INCLASS Input image class
INSEQ 0.0 9999.0 Input image seq. no.
INDISK 0.0 9.0 Input image disk no.
OUTNAME Output image name
OUTCLASS Output image class
OUTSEQ 0.0 9999.0 Output image seq. #
OUTDISK 0.0 9.0 Output image disk drive
BLC BLC of input image
TRC TRC of input image
PIXRANGE Allowed range input values
OPCODE Operator code:
LOG, ALOG, LOGN, EXP,
POWR
CPARM CPARM(1:5):
Output map is formed from
C1+C2*OP[C3*IN+C4]
except for 'POWR' when its
C1+C2*[C3*IN+C4]**C5
HELP SECTION
SCLIM
Type: Task
Use: SCLIM is similar to MATHS but is really designed to produce
images scaled from 0 to 1 with blanked pixels set to zero and
clipped pixels set either to 1 or 0. It operates on an image,
pixel by pixel, with a mathematical function. Current choices
are LOG, LOGN, ALOG, EXP, and POWR. The output images are
mostly used as inputs to LAYER.
Adverbs:
INNAME........Input image name
INCLASS.......Input image class
INSEQ.........Input image seq. #
INDISK........Input image disk drive #
OUTNAME.......Output image name
OUTCLASS......Output image class, blank = OPCODE
OUTSEQ........Output image seq. #
OUTDISK.......Output image disk drive #
BLC...........BLC of input image
TRC...........TRC of input image
PIXRANGE......Clip image below PIXRANGE(1) and above PIXRANGE(2). The
former end up 0.0 and the latter end up either 1.0 or
0.0 depending on CPARM(6). If PIXR(2) <= PIXR(1), the
full range of the input image is used.
OPCODE........LOG and LOGN:
These take the base 10 and base e (natural)
logarithm of the input image. If the input
pixel is <= 0.0, then the output pixel is
blanked.
OUT = C(1) + C(2) * OP [C(3) * (IN + C(4))]
ALOG and EXP:
These take the base 10 and base e (natural)
anti-logarithm of the input image.
OUT = C(1) + C(2) * OP [C(3) * (IN + C(4))]
POWR:
Each OUTput pixel is formed from the INput
pixel according to:
OUT = C(1) + C(2)*[C(3) * (IN+C(4))]**C(5)
Let X = C(3)*(IN+C(4)) The output pixel is
blanked when X is negative, or when X and C(5)
are both zero. The special case of X < 0 and
C(5) = 2.0 is trapped and blanked output pixel
that would usually occur is avoided.
OUT is then scaled linearly from 0 to 1.0.
Special OPCODEs to match FUNCTYPEs in TVLOD are also
allowed. They are 'LN', 'NE', 'SQ', 'NQ', 'LG', NG'.
See EXPLAIN. CPARM(1)-CPARM(5) are ignored with these
OPCODEs.
CPARM.........C(1:5): Additive and multiplicative factors for
the input image. The defaults depend on the
operator
For OP = LOG, ALOG, LOGN, EXP, POWR
C(2) = 0 -> C(2) = 1
C(3) = 0 -> C(3) = 1
C(6) <= 0 -> values above PIXRANGE(2) end up 1
C(6) > 0 -> values above PIXRANGE(2) end up 0
EXPLAIN SECTION
The normal transfer functions used in TV loading are 'LN', 'NE', 'SQ',
'NQ', 'LG', NG'. The translations of these into the terms of SCLIM
are as follows with PIXRANGE(1) called P1 and PIXRANGE(2) called P2.
Linear 'LN' :
OPCODE = 'POWR' but OPCODE = 'POWR' also works
CPARM(1) = 0 CPARM(1) = 0
CPARM(2) = 1 CPARM(2) = 1
CPARM(3) = 1/(P2-P1) CPARM(3) = 1
CPARM(4) = -P1/(P2-P1) CPARM(4) = 0
CPARM(5) = 1 CPARM(5) = 1
Negative linear 'NE' :
OPCODE = 'POWR'
CPARM(1) = 0
CPARM(2) = 1
CPARM(3) = -1/(P2-P1)
CPARM(4) = P2/(P2-P1)
CPARM(5) = 1
Square root 'SQ' :
OPCODE = 'POWR'
CPARM(1) = 0
CPARM(2) = 1
CPARM(3) = 1/(P2-P1)
CPARM(4) = -P1/(P2-P1)
CPARM(5) = 0.5
Negative square root 'NQ' :
OPCODE = 'POWER'
CPARM(1) = 0
CPARM(2) = 1
CPARM(3) = -1/(P2-P1)
CPARM(4) = P2/(P2-P1)
CPARM(5) = 0.5
Logarithmic 'LG' :
OPCODE = 'LOGN'
CPARM(1) = 0.0
CPARM(2) = 1.0/ln(6501.0)
CPARM(3) = 6500.0/(P2-P1)
CPARM(4) = 1.0 - 6500.0 P1/(P2-P1)
CPARM(5) = 0.0
Negative logarithmic 'NG' :
OPCODE = 'LOGN'
CPARM(1) = 0.0
CPARM(2) = 1.0/ln(6501.0)
CPARM(3) = -6500.0/(P2-P1)
CPARM(4) = 1.0 + 6500.0 P2/(P2-P1)
CPARM(5) = 0.0