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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <mach.h>
include <ctype.h>
include <syserr.h>
include <imhdr.h>
include <imio.h>
define FIRST 1
define LAST MAX_LONG
.help imisec
.nf ___________________________________________________________________________
IMISEC -- Translate a section specification string (passed as a suffix
to the imagefile filename) into a set of logical to physical transformation
vectors.
The image section notation is used to access portions of an image, to reduce
the dimensionality of an image, to reverse the coordinates of any of the axes
of an image, and so on. Since this facility is built into IMIO, and is
completely transparent to programs using IMIO, it significantly increases
the power and flexibility of all programs which assess images, without
complicating the applications code.
Examples ("map (image_name, ...)":
image_name meaning
image[*,-*] (flip columns end for end)
image[*,*,5] (band 5 of image cube)
image[*,5,*] (x,y --> x,z)
image[x1:x2,y1:y2] (2-D subraster)
image[x1:x2:n,*] (subsample by N in x)
If the number of dimensions specified in the section is less than the number
of physical dimensions in the image then the higher dimensions default to 1.
If the number of dimensions given is greater than the number of phyiscal
dimensions then the nonphysical excess dimensions must be set to 1.
.endhelp ______________________________________________________________________
procedure imisec (imdes, section)
pointer imdes
char section[ARB]
int ip, i, dim, nsubscripts, nphysdim, nlogdim
long x1[IM_MAXDIM], x2[IM_MAXDIM], step[IM_MAXDIM], clktime()
begin
# Set up null mapping (default). Check for null section string,
# or null section, and return if found.
nphysdim = IM_NDIM(imdes)
call aclrl (IM_VOFF(imdes,1), nphysdim)
call amovkl (long(1), IM_VSTEP(imdes,1), nphysdim)
do dim = 1, nphysdim
IM_VMAP(imdes,dim) = dim
if (section[1] == EOS)
return
else if (section[1] != '[')
call imerr (IM_NAME(imdes), SYS_IMSYNSEC)
ip = 2
while (IS_WHITE(section[ip]))
ip = ip + 1
if (section[ip] == ']')
return
# Decode the section string, yielding the vectors X1, X2, and STEP,
# of length NSUBSCRIPTS.
for (i=1; i <= IM_MAXDIM && section[ip] != ']'; i=i+1)
call im_decode_subscript (section, ip, x1[i], x2[i], step[i])
nsubscripts = i - 1
# Set the transformation vectors. If too few dimensions were given
# set the higher dimensions to 1. If too many dimensions were given
# the higher dimensions must have been set to 1 in the section.
for (dim = nsubscripts + 1; dim <= nphysdim; dim = dim + 1) {
x1[dim] = 1
x2[dim] = 1
step[dim] = 1
}
for (dim = nphysdim + 1; dim <= nsubscripts; dim = dim + 1)
if (x1[dim] != 1 || x2[dim] != 1)
call imerr (IM_NAME(imdes), SYS_IMDIMSEC)
nlogdim = 0
for (dim=1; dim <= nphysdim; dim=dim+1) {
# Set up transformation for a single physical dimension.
call im_ctranset (imdes, dim, x1[dim], x2[dim], step[dim])
# Map logical dimension onto physical dimension.
if (x1[dim] != x2[dim]) {
nlogdim = nlogdim + 1
IM_VMAP(imdes,nlogdim) = dim
IM_LEN(imdes,nlogdim) = IM_LEN(imdes,dim)
}
}
# Convert a zero-dimensional image into a one dimensional image
# of length one pixel (section addresses a single pixel).
if (nlogdim == 0) {
nlogdim = 1
IM_VMAP(imdes,1) = 1
IM_LEN(imdes,1) = 1
}
IM_NDIM(imdes) = nlogdim
IM_MTIME(imdes) = clktime (long(0))
end
# IM_CTRANSET -- Set the logical to physical section coordinate transformation
# coefficients VOFF and VSTEP for the axis DIM. Adjust the length of the
# logical axis IM_LEN if needed.
procedure im_ctranset (imdes, dim, x1_arg, x2_arg, step)
pointer imdes
int dim
long x1_arg, x2_arg, step, x1, x2, length_axis
begin
x1 = x1_arg
if (x1_arg == LAST)
x1 = IM_LEN(imdes,dim)
x2 = x2_arg
if (x2_arg == LAST)
x2 = IM_LEN(imdes,dim)
# Compute the number of pixels in this axis of the section, allowing
# for non-unity step sizes. Set the axis length seen by the calling
# program to this value.
length_axis = (x2 - x1) / step + 1
if (length_axis <= 0)
call imerr (IM_NAME(imdes), SYS_IMSTEPSEC)
else
IM_LEN(imdes,dim) = length_axis
IM_VOFF(imdes,dim) = x1 - step
IM_VSTEP(imdes,dim) = step
end
# IM_DECODE_SUBSCRIPT -- Decode a single subscript expression to produce the
# range of values for that subscript (X1:X2), and the sampling step size, STEP.
# Note that X1 may be less than, greater than, or equal to X2, and STEP may
# be a positive or negative nonzero integer. Various shorthand notations are
# permitted, as is embedded whitespace.
procedure im_decode_subscript (section, ip, x1, x2, step)
char section[ARB]
int ip
long x1, x2, step, temp
int ctol()
define synerr_ 99
begin
x1 = FIRST
x2 = LAST
step = 1
while (IS_WHITE(section[ip]))
ip = ip + 1
# Get X1, X2.
if (ctol (section, ip, temp) > 0) { # [x1
x1 = temp
if (section[ip] == ':') {
ip = ip + 1
if (ctol (section, ip, x2) == 0) # [x1:x2
goto synerr_
} else
x2 = x1
} else if (section[ip] == '-') {
x1 = LAST # [-*
x2 = FIRST
ip = ip + 1
if (section[ip] == '*')
ip = ip + 1
} else if (section[ip] == '*') # [*
ip = ip + 1
while (IS_WHITE(section[ip]))
ip = ip + 1
# Get sample step size, if give.
if (section[ip] == ':') { # ..:step
ip = ip + 1
if (ctol (section, ip, step) == 0)
goto synerr_
else if (step == 0)
goto synerr_
}
# Allow notation such as "-*:5", (or even "-:5") where the step
# is obviously supposed to be negative.
if (x1 > x2 && step > 0)
step = -step
while (IS_WHITE(section[ip]))
ip = ip + 1
if (section[ip] == ',') {
ip = ip + 1
return
} else if (section[ip] == ']')
return
synerr_
# Syntax error in image section specification.
call imerr (section, SYS_IMSYNSEC)
end
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