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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <imhdr.h>
include "wdes.h"
include "crtpict.h"
# CRT_LINEAR_HGRAM -- Calculate two histograms of an image. One histogram
# shows the distribution of intensities in the untransformed image; the other
# shows the distribution of greyscale values in the transformed image. This
# procedure assumes a linear transformation.
procedure crt_linear_hgram (im, gp, z1, z2, ztrans, inten_hgram,greys_hgram)
pointer im # Pointer to image
pointer gp # Graphics descriptor
real z1, z2 # Range of intensities mapped
int ztrans # Type of transfer function - linear or unitary
int inten_hgram[NBINS] # Output array of intensity hgram values
int greys_hgram[NBINS] # Output array of greyscale hgram values
pointer buf
int npix, nsig_bits, zrange, mask, min_val, max_val
long v[IM_MAXDIM]
int dz1, dz2, high_zi, low_zi
real high_z, low_z
bool ggetb()
pointer imgnlr(), imgnli()
int ggeti()
errchk im_minmax, ggeti, imgnli, imgnlr
begin
# If z1 and z2 not in graphcap, set to some reasonable numbers for
# plots to be generated.
if (ggetb (gp, "z1") && ggetb (gp, "z2")) {
dz1 = ggeti (gp, "z1")
dz2 = ggeti (gp, "z2")
} else {
dz1 = 0
dz2 = 255
}
# Calculate number of bits of depth in output device
zrange = ggeti (gp, "zr")
for (nsig_bits = 0; ; nsig_bits = nsig_bits + 1) {
zrange = zrange / 2
if (zrange == 0)
break
}
mask = (2 ** (nsig_bits)) - 1
call aclri (inten_hgram, NBINS)
call aclri (greys_hgram, NBINS)
call amovkl (long(1), v, IM_MAXDIM)
# Read lines into buffer and accumulate histograms.
npix = IM_LEN(im,1)
if (ztrans == W_UNITARY) {
min_val = int (IM_MIN(im))
max_val = int (IM_MAX(im))
while (imgnli (im, buf, v) != EOF) {
call ahgmi (Memi[buf], npix, inten_hgram, NBINS, min_val,
max_val)
call aandki (Memi[buf], mask, Memi[buf], npix)
call ahgmi (Memi[buf], npix, greys_hgram, NBINS, dz1, dz2)
}
} else if (IM_PIXTYPE(im) == TY_SHORT) {
min_val = int (IM_MIN(im))
max_val = int (IM_MAX(im))
if (z2 > z1) {
# Positive contrast
high_zi = int (z2)
low_zi = int (z1)
} else {
# Negative contrast
high_zi = int (z1)
low_zi = int (z2)
}
while (imgnli (im, buf, v) != EOF) {
call ahgmi (Memi[buf], npix, inten_hgram, NBINS, min_val,
max_val)
call ahgmi (Memi[buf], npix, greys_hgram, NBINS, low_zi,
high_zi)
}
} else {
if (z2 > z1) {
# Positive contrast
high_z = z2
low_z = z1
} else {
# Negative contrast
high_z = z1
low_z = z2
}
while (imgnlr (im, buf, v) != EOF) {
call ahgmr (Memr[buf], npix, inten_hgram, NBINS, IM_MIN(im),
IM_MAX(im))
call ahgmr (Memr[buf], npix, greys_hgram, NBINS, low_z, high_z)
}
}
end
# CRT_USER_HGRAM -- Calculate two histograms of an image. One histogram
# shows the distribution of intensities in the untransformed image; the other
# shows the distribution of greyscale values in the transformed image. This
# procedure does not assume a linear transformation, but rather uses a user
# specified look up table.
procedure crt_user_hgram (im, gp, z1, z2, lut, inten_hgram, greys_hgram)
pointer im # Pointer to image
pointer gp # Graphics descriptor
real z1, z2 # Range of intensities mapped
short lut[ARB] # Look up table previously calculated
int inten_hgram[NBINS] # Output array of intensity hgram values
int greys_hgram[NBINS] # Output array of greyscale hgram values
pointer buf, ibuf, sp, rlut
short min_val, max_val, short_min, short_max, dz1, dz2
int npix
long v[IM_MAXDIM]
short high_zi, low_zi
real high_z, low_z
pointer imgnlr(), imgnls()
errchk im_minmax, imgnls, imgnlr
begin
# Get max and min in look up table
call alims (lut, SZ_BUF, dz1, dz2)
call aclri (inten_hgram, NBINS)
call aclri (greys_hgram, NBINS)
call amovkl (long(1), v, IM_MAXDIM)
# Read lines into buffer and accumulate histograms.
npix = IM_LEN(im,1)
if (IM_PIXTYPE(im) == TY_SHORT) {
min_val = short (IM_MIN(im))
max_val = short (IM_MAX(im))
short_min = short (STARTPT)
short_max = short (ENDPT)
if (z2 > z1) {
# Positive contrast
high_zi = short (z2)
low_zi = short (z1)
} else {
# Negative contrast
high_zi = short (z1)
low_zi = short (z2)
}
while (imgnls (im, buf, v) != EOF) {
call ahgms (Mems[buf], npix, inten_hgram, NBINS, min_val,
max_val)
call amaps (Mems[buf], Mems[buf], npix, low_zi, high_zi,
short_min, short_max)
call aluts (Mems[buf], Mems[buf], npix, lut)
call ahgms (Mems[buf], npix, greys_hgram, NBINS, dz1, dz2)
}
} else {
if (z2 > z1) {
# Positive contrast
high_z = z2
low_z = z1
} else {
# Negative contrast
high_z = z1
low_z = z2
}
call smark (sp)
call salloc (ibuf, npix, TY_INT)
call salloc (rlut, SZ_BUF, TY_REAL)
call achtsr (lut, Memr[rlut], SZ_BUF)
while (imgnlr (im, buf, v) != EOF) {
call ahgmr (Memr[buf], npix, inten_hgram, NBINS, IM_MIN(im),
IM_MAX(im))
call amapr (Memr[buf], Memr[buf], npix, z1, z2, STARTPT, ENDPT)
call achtri (Memr[buf], Memi[ibuf], npix)
call alutr (Memi[ibuf], Memr[buf], npix, Memr[rlut])
call ahgmr (Memr[buf], npix, greys_hgram, NBINS, real (dz1),
real (dz2))
}
call sfree (sp)
}
end
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