1HAFTON(3NCARG)                   NCAR GRAPHICS                  HAFTON(3NCARG)
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NAME

6       HAFTON - draws a half-tone picture from data stored in a rectangular
7       array with the intensity in the picture proportional to the data value.
8

UTILITY

10       This routine is part of the Halftone utility in NCAR Graphics. To see
11       the overview man page for this utility, type "man halftone".
12

STATUS

14       HAFTON is obsolete.  It has been replaced by the CPCICA entry of the
15       Conpack contouring package.
16
17       HAFTON continues to be provided for compatibility of early NCAR
18       Graphics codes.  If you are writing new code, we suggest that you use
19       CPCICA.
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SYNOPSIS

22       CALL HAFTON (Z,L,M,N,FLO,HI,NLEV,NOPT,NPRM,ISPV,SPVAL)
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DESCRIPTION

25       Z           (an input array of type REAL) defining a two-dimensional
26                   field to be half-tone plotted. A subset of Z of extent M by
27                   N can be plotted.
28
29       L           (an input parameter of type INTEGER) which is the first
30                   dimension of the Z array.
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32       M           (an input parameter of type INTEGER) which is the extent of
33                   the first dimension of array Z to be plotted.  This allows
34                   for a sub-array of Z to be plotted.  M must be less than or
35                   equal to L.
36
37       N           (an input parameter of type INTEGER) which is the extent of
38                   the second dimension of array Z to be plotted.  This allows
39                   for a sub-array of Z to be plotted.  N must be less than or
40                   equal to the second dimension of Z.
41
42       FLO         (an input parameter of type REAL) defining a lowest level
43                   for plotting.  If FLO = HI = 0., the minimum value of Z
44                   will be generated by HAFTON.
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46       HI          (an input parameter of type REAL) defining a highest level
47                   for plotting.  If HI = FLO = 0., the maximum value of Z
48                   will be generated by HAFTON.
49
50       NLEL        (an input parameter of type INTEGER) specifying the number
51                   of intensity levels desired.  16 maximum.  If NLEV = 0 or
52                   1, 16 levels are used.
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54       NOPT        (an input parameter of type INTEGER) used to control the
55                   mapping of Z onto the intensities.  The sign of NOPT
56                   controls the directness or inverseness of the mapping.
57
58                   NOPT positive yields direct mapping.  The largest value of
59                   Z produces the most dense dots.  On mechanical plotters,
60                   large values of Z will produce a dark area on the paper.
61                   With the film development methods used at NCAR, large
62                   values of Z will produce many (white) dots on the film,
63                   also resulting in a dark area on reader-printer paper.
64
65                   NOPT negative yields inverse mapping.  The smallest values
66                   of Z produce the most dense dots resulting in dark areas on
67                   the paper.
68
69                   The absolute value of NOPT determines the mapping of Z onto
70                   the intensities.  For IABS(NOPT)
71
72                   = 0  The mapping is linear.  For
73                        each intensity there is an equal
74                        range in Z value.
75
76                   = 1  The mapping is linear.  For
77                        each intensity there is an equal
78                        range in Z value.
79
80                   = 2  The mapping is exponential.  For
81                        larger values of Z, there is a
82                        larger difference in intensity for
83                        relatively close values of Z.  Details
84                        in the larger values of Z are displayed
85                        at the expense of the smaller values
86                        of Z.
87
88                   = 3  The mapping is logarithmic, so
89                        details of smaller values of Z are show
90                        at the expense of larger values of Z.
91
92                   = 4  Sinusoidal mapping, so mid-range values
93                        of Z show details at the expense of
94                        extreme values of Z.
95
96                   = 5  Arcsine mapping, so extreme values of
97                        Z are shown at the expense of mid-range
98
99       NPRM        (an input parameter of type INTEGER) used to control the
100                   drawing of a perimeter around the half-tone picture.
101
102                   NPRM=0:  The perimeter is drawn with ticks pointing at data
103                   locations.  (Side lengths are proportional to number of
104                   data values.)
105
106                   NPRM positive:  No perimeter is drawn.  The picture fills
107                   the frame.
108
109                   NPRM negative:  The picture is within the confines of the
110                   user's current viewport setting.
111
112       ISPV        (an input parameter of type INTEGER) used to tell if the
113                   special value feature is being used.  The special value
114                   feature is used to mark areas where the data is not known
115                   or holes are wanted in the picture.
116
117                   ISPV = 0:  Special value feature not in use.  SPVAL is
118                   ignored.
119
120                   ISPV non-zero:  Special value feature in use.  SPVAL
121                   defines the special value.  Where Z contains the special
122                   value, no half-tone is drawn.  If ISPV
123
124                   = 0  Special value feature not in use.
125                        SPVAL is ignored.
126
127                   = 1  Nothing is drawn in special value
128                        area.
129
130                   = 2  Contiguous special value areas are
131                        surrounded by a polygonal line.
132
133                   = 3  Special value areas are filled
134                        with X(s).
135
136                   = 4  Special value areas are filled in
137                        with the highest intensity.
138
139       SPVAL       (an iput parameter of type REAL) used to denote missing
140                   values in the Z array.  This argument is ignored if ISPV =
141                   0.
142

ACCESS

144       To use HAFTON, load the NCAR Graphics libraries ncarg, ncarg_gks, and
145       ncarg_c, preferably in that order.
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SEE ALSO

148       Online: halftone, ezhftn, halftone_params, conpack, conpack_params,
149       cpcica
150
151       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial; NCAR Graphics
152       Fundamentals, UNIX Version; User's Guide for NCAR GKS-0A Graphics
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155       Copyright (C) 1987-2009
156       University Corporation for Atmospheric Research
157       The use of this Software is governed by a License Agreement.
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161UNIX                              March 1993                    HAFTON(3NCARG)
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