image — GMT 6.5.0 documentation

# image

Plot raster or EPS images

## Synopsis

gmt image imagefile [ -B[p|s]parameters ] [ -D refpoint ] [ -F box ] [ -G[color][+b|f|t] ] [ -I ] [ -J parameters ] [ -J z|Zparameters ] [ -M ] [ -R west/east/south/north[/zmin/zmax][+r][+uunit] ] [ -U[stamp] ] [ -V[level] ] [ -X[a|c|f|r][xshift] ] [ -Y[a|c|f|r][yshift] ] [ -p flags ] [ -t transp ] [ --PAR=value ]

## Description

image reads an Encapsulated PostScript file or a raster image file and plots it on a map. The image can be scaled arbitrarily, and 1-bit raster images can be (1) inverted, i.e., black pixels (on) becomes white (off) and vice versa, or (2) colorized, by assigning different foreground and background colors, and (3) made transparent where one of back- or foreground is painted only. As an option, the user may choose to convert colored raster images to grayscale using TV’s YIQ-transformation. For raster files, the user can select which color to be made transparent. The user may also choose to replicate the image which, when preceded by appropriate clip paths, may allow larger custom-designed fill patterns to be implemented (the -Gp mechanism offered in most GMT programs is limited to rasters smaller than 146 by 146).

## Required Arguments

imagefile

  This must be an Encapsulated PostScript (EPS) file or a raster image. An EPS file must contain an appropriate BoundingBox. A raster file can have a depth of 1, 8, 24, or 32 bits and is read via GDAL.

## Optional Arguments

-B[p|s]parameters

  Set map boundary frame and axes attributes. (See full description) (See cookbook information).

-D[g|j|J|n|x]refpoint+rdpi[c]+w[-]width[/height][+jjustify][+nnx[/ny] ][+odx[/dy]]

  Sets reference point on the map for the image using one of four coordinate systems:

  - g - Append lon/lat for map coordinates. Requires both -R and -J to be set.

  - j - Append code to j or Jcode for setting the refpoint via a 2-char justification code that refers to the (invisible) projected map bounding box. Requires both -R and -J to be set. Upper case means justify on the outside.

  - n - Append xn/yn for normalized bounding box coordinates (0-1). Requires both -R and -J to be set.

  - x - Append x/y for plot coordinates (append cm, inch, or ppoint).

  By default, the anchor point on the scale is assumed to be the bottom left corner (BL), but this can be changed by appending +j followed by a 2-char justification code justify (see text). Note: If -Dj is used then justify defaults to the same as refpoint, if -DJ is used then justify defaults to the mirror opposite of refpoint. Specify image size in one of two ways:

  - +n - Append nx[/ny] to replicate the (scaled) image nx times horizontally and ny times vertically. If ny is omitted, it will be identical to nx [Default is 1/1].

  - +r - Specify dpi to set the dpi of the image in dots per inch, or append c to indicate this is dots per cm [inches].

  - +w - Append [-]width[/height] to set the width (and height) of the image in plot coordinates (inches, cm, etc.). If height (or width) is set to 0, then the original aspect ratio of the image is maintained. If width (or height) is negative we use the absolute value and interpolate image to the device resolution using the PostScript image operator. If neither dimensions nor dpi are set then we revert to the default dpi [GMT_GRAPHICS_DPU].

-F[+cclearances][+gfill][+i[[gap/]pen]][+p[pen]][+r[radius]][+s[[dx/dy/][shade]]]

> Without further options, draws a rectangular border around the image using MAP_FRAME_PEN. The following modifiers can be appended to -F, with additional explanation and examples provided in the The background panel cookbook section:

> - +c - Set clearance where clearance is either gap, xgap/ygap, or lgap/rgap/bgap/tgap and gap gives a uniform clearance, xgap/ygap gives separate clearances in the x- and y- directions, and lgap/rgap/bgap/tgap gives individual clearances between the map embellishment and the border for each side.

> - +g - Give fill to fill the box with a color specified by fill [default is no fill].

> - +i - Draw a secondary, inner border border outline [[gap/]pen]. Optionally, append the gap between the inner and outer border and the pen for the inner border [default is a uniform gap between borders of 2p and the MAP_DEFAULT_PEN].

> - +p - append pen to specify different pen attributes for the box outline.

> - +r - Draw a rounded rectangular borders instead of sharp with a corner radius set by radius (append units) [defaults is 6p].

> - +s - Place an offset background shaded region behind the box. Here, dx/dy indicates the shift relative to the foreground frame [default is 4p/-4p] and shade sets the fill style to use for shading [default is gray50].

-G[color][+b|f|t]

  Change certain pixel values to another color or make them transparent.

  - +b - For 1-bit images you can specify an alternate color for the background pixels. Give no color to make those pixels transparent.

  - +f - For 1-bit images you can specify an alternate color for the foreground pixels. Give no color to make those pixels transparent.

  - +t - For color images you can select a single color that should be made transparent instead. This option may be repeated with different settings.

-I

  Invert 1-bit image before plotting. This is what is done when you use -GP to invert patterns in other GMT plotting programs. Ignored if used with color images.

-Jparameters

  Specify the projection. (Used only with -p)

-M

  Convert color image to monochrome grayshades using the (television) YIQ-transformation.

-Rxmin/xmax/ymin/ymax[+r][+uunit]

  Specify the region of interest. (Used only with -p) (See full description) (See cookbook information).

> For perspective view -p, optionally append /zmin/zmax. (more …)

-U[label|+c][+jjustify][+odx[/dy]][+ttext]

  Draw GMT time stamp logo on plot. (See full description) (See cookbook information).

-V[level]

  Select verbosity level [w]. (See full description) (See cookbook information).

-X[a|c|f|r][xshift]

  Shift plot origin. (See full description) (See cookbook information).

-Y[a|c|f|r][yshift]

  Shift plot origin. (See full description) (See cookbook information).

-p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0] (more …)

  Select perspective view. (Requires -R and -J for proper functioning).

-ttransp[/transp2] (more …)

  Set transparency level(s) in percent.

-^ or just -

  Print a short message about the syntax of the command, then exit (Note: on Windows just use -).

-+ or just +

  Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exit.

-? or no arguments

  Print a complete usage (help) message, including the explanation of all options, then exit.

--PAR=value

  Temporarily override a GMT default setting; repeatable. See gmt.conf for parameters.

## Notes

The -G and -I options are for raster images only. They have no effect when placing Encapsulated PostScript files.

## Examples

Note: Since many GMT plot examples are very short (i.e., one module call between the gmt begin and gmt end commands), we will often present them using the quick modern mode GMT Modern Mode One-line Commands syntax, which simplifies such short scripts.

To plot the remote image needle.jpg, scaling it be 7 cm wide (height is scaled accordingly), use:

    gmt image @needle.jpg -Dx0/0+w7c -pdf plot

To plot the same file but reversing the bands, use:

    gmt image @needle.jpg+b2,1,0 -Dx0/0+w7c -pdf plot

To only plot its red band as gray shade, use:

    gmt image @needle.jpg+b0 -Dx0/0+w7c -pdf plot

To include an Encapsulated PostScript file gallo.eps with its upper right corner 2 inch to the right and 1 inch up from the current location, and have its width scaled to 3 inches, while keeping the aspect ratio, use:

    gmt image @gallo.eps -Dx2i/1i+jTR+w3i -pdf image

To replicate the 1-bit remote raster image vader1.png, colorize it (dark gray background and yellow foreground), and setting each of 6 by 12 tiles to be 2.5 cm wide, use:

    gmt image @vader1.png -Gdarkgray+b -Gyellow+f -Dx0/0+w2.5c+n6/12 -pdf image

## See Also

gmt, gmtcolors, gmtlogo legend, colorbar plot, psconvert