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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <imhdr.h>
include <mach.h>
include "wdes.h"
include "crtpict.h"
# CRT_ESTABLISH_TRANSFORM -- Set up both the spatial and greyscale mapping.
# The window descriptor "wdes" is filled.
procedure crt_establish_transform (gp, im, cl, wdes)
pointer gp
pointer im
pointer cl
pointer wdes
int w1, len_stdline
real z1, z2
bool fp_equalr()
int strncmp()
errchk crt_xy_scale, strcmp, im_minmax, zscale
begin
# Procedure xy_scale calculates and stores the spatial
# transformation fields of structure wdes.
call crt_xy_scale (gp, cl, im, wdes)
w1 = W_WC(wdes, 1)
# Now for the intensity to greyscale mapping. Values z1 and z2,
# the intensities that map to the lowest and highest greyscale
# levels, are calculated and stored in the wdes structure. First,
# set up the default values. These will not be changed if
# ztrans = "user".
W_ZT(w1) = W_USER
z1 = INDEFR
z2 = INDEFR
# Put up to date min, max values in the header structure, if necessary
if (IM_LIMTIME(im) < IM_MTIME(im))
call im_minmax (im, IM_MIN(im), IM_MAX(im))
if (strncmp (ZTRANS(cl), "min_max", 1) == 0) {
W_ZT(w1) = W_LINEAR
if (Z1(cl) != Z2(cl)) {
# Use values set by user
z1 = Z1(cl)
z2 = Z2(cl)
} else {
# Use image min and max unless the user has set the contrast
# parameter to alter the slope of the transfer function.
if (abs (CONTRAST(cl) - 1.0) > EPSILON) {
# CONTRAST = 1.0
z1 = IM_MIN(im)
z2 = IM_MAX(im)
} else if (abs (CONTRAST(cl) + 1.0) > EPSILON) {
# CONTRAST = -1.0
z1 = IM_MAX(im)
z2 = IM_MIN(im)
} else {
len_stdline = SAMPLE_SIZE / NSAMPLE_LINES(cl)
call zscale (im, z1, z2, CONTRAST(cl), SAMPLE_SIZE,
len_stdline)
}
}
}
if (strncmp (ZTRANS(cl), "auto", 1) == 0) {
W_ZT(w1) = W_LINEAR
# Calculate optimum z1 and z2 from image mode
len_stdline = SAMPLE_SIZE / NSAMPLE_LINES(cl)
call zscale (im, z1, z2, CONTRAST(cl), SAMPLE_SIZE, len_stdline)
if (IM_PIXTYPE(im) == TY_SHORT) {
if (short (z1) == short (z2))
call error (0,
"No range in data, ztrans=auto failed: z1 = z2")
}
else if (fp_equalr (z1, z2))
call error (0, "No range in data, ztrans=auto failed: z1=z2")
}
# Set the intensity extremes of the window descriptor
if (strncmp (ZTRANS(cl), "none", 1) == 0) {
W_ZT(w1) = W_UNITARY
W_ZS(w1) = IM_MIN(im)
W_ZE(w1) = IM_MAX(im)
} else {
W_ZS(w1) = z1
W_ZE(w1) = z2
}
end
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