1GMT2RGB(1) Generic Mapping Tools GMT2RGB(1)
2
6 gmt2rgb - Converting a grid file, a raw, or a Sun raster file to r/g/b
7 grids
8
10 gmt2rgb infile -Gtemplate [ -Ccptfile ] [ -F ] [
11 -Ixinc[m|c][/yinc[m|c]] ] [ -Llayer ] [ -Rxmin/xmax/ymin/ymax[r] ] [ -V
12 ] [ -Wwidth/height[/n_bytes]
13
15 gmt2rgb reads one of three types of input files: (1) A Sun 8-, 24-, or
16 32-bit raster file; we the write out the red, green, and blue compo‐
17 nents (0-255 range) to separate grid files. Since the raster file
18 header is limited you may use the -R, -F, -I options to set a complete
19 header record [Default is simply based on the number of rows and col‐
20 umns]. (2) A binary 2-D grid file; we then convert the z-values to red,
21 green, blue via the provided cpt file. Optionally, only write out one
22 of the r, g, b, layers. (3) A RGB or RGBA raw raster file. Since raw
23 rastefiles have no header, you have to give the image dimensions via
24 the -W option.
25 infile The (1) Sun raster file, (2) 2-D binary grid file, or (3) raw
27 raster file to be converted.
28 -G Provide an output name template for the three output grids. The
30 template should be a regular grid file name except it must con‐
31 tain the string %c which on output will be replaced by r, g, or
32 b.
33
35 -C name of the color palette table (for 2-D binary input grid
36 only).
37 -F Force pixel node registration [Default is gridline registra‐
39 tion]. (Node registrations are defined in GMT Cookbook Appendix
40 B on grid file formats.)
41 -I x_inc [and optionally y_inc] is the grid spacing. Optionally,
43 append a suffix modifier. Geographical (degrees) coordinates:
44 Append m to indicate arc minutes or c to indicate arc seconds.
45 If one of the units e, k, i, or n is appended instead, the
46 increment is assumed to be given in meter, km, miles, or nauti‐
47 cal miles, respectively, and will be converted to the equivalent
48 degrees longitude at the middle latitude of the region (the con‐
49 version depends on ELLIPSOID). If /y_inc is given but set to 0
50 it will be reset equal to x_inc; otherwise it will be converted
51 to degrees latitude. All coordinates: If = is appended then the
52 corresponding max x (east) or y (north) may be slightly adjusted
53 to fit exactly the given increment [by default the increment may
54 be adjusted slightly to fit the given domain]. Finally, instead
55 of giving an increment you may specify the number of nodes
56 desired by appending + to the supplied integer argument; the
57 increment is then recalculated from the number of nodes and the
58 domain. The resulting increment value depends on whether you
59 have selected a gridline-registered or pixel-registered grid;
60 see Appendix B for details.
61 -L Output only the specified layer (r, g, or b). [Default outputs
63 all 3 layers].
64 -R xmin, xmax, ymin, and ymax specify the Region of interest. For
66 geographic regions, these limits correspond to west, east,
67 south, and north and you may specify them in decimal degrees or
68 in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left
69 and upper right map coordinates are given instead of w/e/s/n.
70 The two shorthands -Rg and -Rd stand for global domain (0/360
71 and -180/+180 in longitude respectively, with -90/+90 in lati‐
72 tude). For calendar time coordinates you may either give (a)
73 relative time (relative to the selected TIME_EPOCH and in the
74 selected TIME_UNIT; append t to -JX|x), or (b) absolute time of
75 the form [date]T[clock] (append T to -JX|x). At least one of
76 date and clock must be present; the T is always required. The
77 date string must be of the form [-]yyyy[-mm[-dd]] (Gregorian
78 calendar) or yyyy[-Www[-d]] (ISO week calendar), while the clock
79 string must be of the form hh:mm:ss[.xxx]. The use of delim‐
80 iters and their type and positions must be exactly as indicated
81 (however, input, output and plot formats are customizable; see
82 gmtdefaults).
83 -V Selects verbose mode, which will send progress reports to stderr
85 [Default runs "silently"].
86 -W Sets the size of the raw raster file. By default an RGB file
88 (which has 3 bytes/pixel) is assumed. For RGBA files use
89 n_bytes = 4. Use -W for guessing the image size of a RGB raw
90 file, and -W=/=/4 if the raw image is of the RGBA type. Notice
91 that this might be a bit slow because the guessing algorithm
92 makes uses of FFTs.
93
95 To use the color palette topo.cpt to create r, g, b component grids
96 from hawaii_grv.grd file, use
97 gmt2rgb hawaii_grv.grd -Ctopo.cpt -Ghawaii_grv_%c.grd
99 To output the red component from the Sun raster radiation.ras file, use
101 gmt2rgb radiation.ras -Lr -Gcomp_%c.grd
103
105 gmtdefaults(1), GMT(1), grdedit(1), grdimage(1), grdmath(1), grdview(1)
106GMT 4.3.1 15 May 2008 GMT2RGB(1)