; MATHS
;---------------------------------------------------------------
;! operates on an image with a choice of mathematical functions
;# Task Analysis
;-----------------------------------------------------------------------
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MATHS LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC
MATHS: Task to operate on an image with mathematical functions
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
OPCODE Operator code:
SIN, COS, TAN, ASIN, ACOS,
ATAN, LOG, ALOG, LOGN, EXP,
POLY, DIVP, POWR, MOD, ABS
CPARM CPARM(1:5):
Output map is formed from
C1+C2*OP[C3*IN+C4]
except for 'POLY' when its
C1+C2*IN+C3*IN**2+C4*IN**3
'DIVP' when its
C1+C2/IN+C3/IN**2+C4/IN**3
'POWR' when its
C1+C2*[C3*IN+C4]**C5
and 'MOD' when its
C1+C2*MOD[C3*IN+C4, C5]
CPARM(6) <= 0 -> all output
undefined pixels are magic
blanked, else zeroes used
---------------------------------------------------------------
MATHS
Type: Task
Use: Operate on an image, pixel by pixel, with a mathematical
function. Current choices are SIN, COS, TAN, ASIN, ACOS, ATAN,
LOG, LOGN, ALOG, EXP, POLY, DIVP, POWR, and MOD. Undefined
output pixels are either magic value blanked or zeroed.
NO checks for overflows which may occur with some of these
operators are made, since they depend on your computer.
For example, with TAN, if the absolute value of an input
pixel is very close say, 90 degrees, then an overflow may
occur.
Note also that the FORTRAN 77 standard trigonometric functions
require arguments in radians. Thus, there is some loss of
accuracy in converting the input data to radians. For example,
for OPCODE='SIN', if an input pixel has a value of 180.0 degrees
then the output pixel will not be identically zero, usually a
small negative number of the order of 1E-9 will result.
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
OPCODE........SIN, COS, and TAN:
The input image units should be DEGREES. If
not, you could use CPARM(3) to rescale them.
For OPCODE = 'TAN', if the input pixel is one of
...-270, -90, 90, 270... then the output pixel
is blanked.
OUT = C(1) + C(2) * OP [C(3) * IN + C(4)]
ASIN, ACOS, and ATAN:
The output image units are DEGREES in the range:
ASIN -90 < THETA < 90
ACOS 0 < THETA < 180
ATAN -90 < THETA < 90
For ASIN and ACOS, if the input pixel is < -1.0
or > 1.0, then the output pixel is blanked.
OUT = C(1) + C(2) * OP [C(3) * IN + C(4)]
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)]
POLY:
Every OUTput pixel is formed from the INput
pixel according to:
OUT = C(1) + C(2)*IN + C(3)*IN*IN + C(4)*IN*IN*IN
DIVP:
Every OUTput pixel is formed from the INput
pixel according to:
OUT = C(1) + C(2)/IN + C(3)/IN/IN + C(4)/IN/IN/IN
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) If C(5) is not an integer,
the output pixel is blanked when X is negative, or
when X and C(5) are both zero.
MOD:
Each OUTput pixel is formed from the INput
pixel according to:
OUT = C(1) + C(2)* MOD [C(3)*IN+C(4), C(5)]
The output pixel is blanked when C(5) = 0.0
ABS:
Each OUTput pixel is formed from the INput
pixel according to:
OUT = C(1) + C(2)* ABS [C(3)*IN+C(4)]
IF all C are zeros, then:
OUT = ABS[IN]
CPARM.........C(1:5): Additive and multiplicative factors for
the input image. The defaults depend on the
operator
For OP = SIN, COS, TAN, ASIN, ACOS, ATAN, LOG,
ALOG, LOGN, EXP, POWR, MOD, ABS
C(2) = 0 -> C(2) = 1
C(3) = 0 -> C(3) = 1
For OP = POLY and DIVP, there are no CPARM defaults
C(6) <= 0 -> all undefined output pixels magic
blanked
C(6) > 0 -> all undefined output pixels zeroed
Note that this includes input pixels
that were magic blanked
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