AIPS HELP file for RGBMP in 31DEC24
As of Thu Apr 25 21:27:57 2024
RGBMP: Task to create an RGB image from the 3rd dim of an image
INPUTS
INNAME Input name(name).
INCLASS Input name(class).
INSEQ 0.0 9999.0 Input name(seq. #). 0=> high
INDISK 0.0 9.0 Input disk drive #. 0=> any
OUTNAME Output name(name).
OUTCLASS Output name(class).
OUTSEQ -1.0 9999.0 Output name(seq. #).
0 => highest unique
OUTDISK 0.0 9.0 Output image disk drive #
0 => highest with space
BLC Bottom left corner of input
TRC Top right corner of input
OPTYPE Allows experimental summing
algorithms, else additive
FUNCTYPE Image intensity transfer func
'L2' Very logarithmic
'LG' Logarithmic
'SQ' Square root
else linear
PIXRANGE Image intensity extrema
allowed
FACTOR 0.0 10.0 Scale "optical depths"
HELP SECTION
RGBMP
Type: Task
Use: RGBMP will create a new cube with 3 planes from the weighted
planes of an input cube. The 3 planes can then be used to
display the 3rd dimension as color on the TV or with display
tasks such as GREYS, PCNTR, and KNTR.
There are a number of experimental algorithms for summing the
images into the 3 colors. The default is a simple sum, weighted
by "triangles in color:
1 *---------------------------*
| * * |
| * * |
| * Green * |
| * * |
| Blue * * Red |
| * * |
0 |-------------*--------------
where the Green is weighted down by ~1/2 since ~2 times as many
channels contribute. All other algorithms use this basic
color weighting and adjust other parameters,
If the third axis has a positive increment, then the first
channel on that axis is the most blue as shown above. Else,
the last channel is the most blue. If the axis type begins
with FREQ, this convention is reversed.
Adverbs:
INNAME......Input name of image(name). Standard defaults.
INCLASS.....Input name of image(class). Standard defaults.
INSEQ.......Input name of image(seq. #). 0 => highest.
INDISK......Disk drive # of image. 0 => any.
OUTNAME.....Output name of image(name). Standard defaults.
OUTCLASS....Output name of image(class). Standard defaults.
OUTSEQ......Output name of image(seq. #). 0 => highest unique
OUTDISK.....Disk drive # of Output image. 0 => highest with
space.
BLC.........The bottom left-hand pixel of the input image
which becomes the bottom left corner of the
new image. The value (0,0) means (1,1).
TRC.........The top right-hand pixel of the input image
which becomes the top right corner of the
new image. The value (0,0) means take the top
right hand corner of the image.
******* Experimental algorithm parameters ***********
OPTYPE......Other than for the special values below, the output is
the simple sum of the channel weights times the image at
each channel.
Current special values are 'CLIP', 'CLIS', 'OPTD',
'OPT2', 'POPT', and 'POP2'. See EXPLAIN.
FUNCTYPE....'SQ' square root, 'LG' logarithmic [log10(1+9*x)],
'L2' [0.5*log(1+99*X)] else linear to scale the image
intensities in PIXRANGE to 0-1. Used only if OPTYPE is
a special value.
PIXRANGE....Clip image values below PIXRANGE(1) and above
PIXRANGE(2) in converting the scale. Used only if
OPTYPE is a special value.
FACTOR......The "optical depth" is the scaled image values times
FACTOR. Used only if OPTYPE is a special value.
EXPLAIN SECTION
In order to offer a variety of ways to sum the image planes, a number
of experimental algorithms are available under control of OPTYPE,
enhanced with adverbs FUNCTYPE, PIXRANGE, and FACTOR. Current special
values for OPTYPE are 'CLIP', 'CLIS', 'OPTD', 'OPT2', 'POPT', and
'POP2'. All of the special algorithms can produce good RGB images and
all can prduce useless ones.
If the input image at each plane of the cube is
Bi (x,y)
then for all OPTYPEs other than the special value
Ti(x,y) = Bi(x,y)
while for all special OPTYPEs, the clipped image is
Ci(x,y) = MAX (PIXRANGE(1), MIN (PIXRANGE(2), Bi(x,y)))
For OPTYPE 'CLIP' when PIXRANGE(1) > 0,
if Ci(x,y)=PIXRANGE(1) then Ti(x,y) = 0
else Ti(x,y) = Ci(x,y)
For all special OPTYPEs except CLIP, the image is then scaled and
warped to values between zero and one by
z(x,y) = (Ci(x,y)-PIXRANGE(1)) / (PIXRANGE(2)-PIXRANGE(1))
z(x,y) = min (1.0, max (0.0, z(x,y)))
Si(x,y) = F[z]
where if FUNCTYPE='LN' F(z) = z
'SQ' F(z) = sqrt (z)
'LG' F(z) = log10 (9*z + 1.0)
'L2' F(z) = 0.5 * log10 (99*z + 1.0)
For OPTYPE = 'CLIS', Ti(x,y) = Si(x,y).
The "optical depth" associated with Si(x,y) is then
t(x,y) = FACTOR * Si(x,y)
OPTYPEs 'POPT' and 'OPTD' then compute
Ti(x,y) = Si(x,y) * (1 - exp(-t(x,y)))
while OPTYPEs 'POP2' and 'OPT2' then compute
Ti(x,y) = Bi(x,y) * (1 - exp(-t(x,y)))
For all OPTYPEs except 'OPTD' and 'OPT2', the Ti(x,y) computed above
and then weighted by the channel/color weight is summed:
SUM(i) = Wi Ti(x,y) + SUM(i-1)
For OPTYPEs 'OPTD' and 'OPT2' however, the previous sum is "absorbed"
by the current optical depth:
SUM(i) = Wi Ti(x,y) + SUM(i-1) * exp(-t(x,y))
Clearly, in this case, the order in which the channels are summed is
important and may be changed by running TRANS with TRANSCODE='12-3'.