Wrapper method for image (#241)

Simple wrapper method. Doesn't do any IO (delegates to GMT).

Author: seisman

doc/api/index.rst

@@ -27,6 +27,7 @@ Plotting data and laying out the map:
     Figure.grdcontour
     Figure.grdimage
     Figure.logo
+    Figure.image
 
 Saving and displaying the figure:
 

gmt/base_plotting.py

@@ -494,7 +494,7 @@ def logo(self, **kwargs):
         D : str
             ``'[g|j|J|n|x]refpoint+wwidth[+jjustify][+odx[/dy]]'``.
             Sets reference point on the map for the image.
-        F: bool or str
+        F : bool or str
             Without further options, draws a rectangular border around the
             GMT logo.
         {U}
@@ -505,3 +505,36 @@ def logo(self, **kwargs):
             raise GMTInvalidInput("Option D must be specified.")
         with Session() as lib:
             lib.call_module("logo", build_arg_string(kwargs))
+
+    @fmt_docstring
+    @use_alias(R="region", J="projection")
+    @kwargs_to_strings(R="sequence")
+    def image(self, imagefile, **kwargs):
+        """
+        Place images or EPS files on maps.
+
+        Reads an Encapsulated PostScript file or a raster image file and plots it on a map.
+
+        {gmt_module_docs}
+
+        {aliases}
+
+        Parameters
+        ----------
+        {J}
+        {R}
+        D: str
+            ``'[g|j|J|n|x]refpoint+rdpi+w[-]width[/height][+jjustify][+nnx[/ny]][+odx[/dy]]'``
+            Sets reference point on the map for the image.
+        F : bool or str
+            ``'[+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**.
+        M : bool
+            Convert color image to monochrome grayshades using the (television)
+            YIQ-transformation.
+        """
+        kwargs = self._preprocess(**kwargs)
+        with Session() as lib:
+            arg_str = " ".join([imagefile, build_arg_string(kwargs)])
+            lib.call_module("image", arg_str)

gmt/tests/baseline/test_image.png

@@ -0,0 +1,19 @@
+"""
+Tests image.
+"""
+import os
+
+import pytest
+
+from .. import Figure
+
+
+TEST_IMG = os.path.join(os.path.dirname(__file__), "baseline", "test_logo.png")
+
+
+@pytest.mark.mpl_image_compare
+def test_image():
+    "Place images on map"
+    fig = Figure()
+    fig.image(TEST_IMG, D="x0/0+w1i", F="+pthin,blue")
+    return fig