Short docu that y-axis is flipped for image plots

due to origin being lower, not higher as is default in maptlotlib

docs/vis.rst

@@ -3,6 +3,9 @@ The vis visualization submodule
 
 General empyre.vis docu here!
 
+Note that the y-axis of all image plots is flipped in comparison to ``matplotlib.pyplot.imshow``, i.e. that the
+origin is `'lower'` in this case instead of `'upper'`.
+
 
 The plot2d module
 -----------------

src/empyre/vis/plot2d.py

@@ -50,7 +50,9 @@ def imshow(field, axis=None, cmap=None, **kwargs):
 
     Notes
     -----
-    Additional kwargs are passed to `matplotlib.pyplot.imshow`.
+    Additional kwargs are passed to :function:`~matplotlib.pyplot.imshow`.
+    Note that the y-axis of the plot is flipped in comparison to :function:`~matplotlib.pyplot.imshow`, i.e. that the
+    origin is `'lower'` in this case instead of `'upper'`.
     Uses the `empyre-image` stylesheet settings for plotting (and axis creation if none exists, yet).
     Fields are squeezed before plotting, so non-2D fields work as long as their superfluous dimensions have length 1.
 
@@ -114,6 +116,8 @@ def contour(field, axis=None, **kwargs):
     Notes
     -----
     Additional kwargs are passed to `matplotlib.pyplot.contour`.
+    Note that the y-axis of the plot is flipped in comparison to :function:`~matplotlib.pyplot.imshow`, i.e. that the
+    origin is `'lower'` in this case instead of `'upper'`.
     Uses the `empyre-image` stylesheet settings for plotting (and axis creation if none exists, yet).
     Fields are squeezed before plotting, so non-2D fields work as long as their superfluous dimensions have length 1.
 
@@ -164,6 +168,8 @@ def colorvec(field, axis=None, **kwargs):
     Notes
     -----
     Additional kwargs are passed to `matplotlib.pyplot.imshow`.
+    Note that the y-axis of the plot is flipped in comparison to :function:`~matplotlib.pyplot.imshow`, i.e. that the
+    origin is `'lower'` in this case instead of `'upper'`.
     Uses the `empyre-image` stylesheet settings for plotting (and axis creation if none exists, yet).
     Fields are squeezed before plotting, so non-2D fields work as long as their superfluous dimensions have length 1.
     Even though squeezing takes place, `colorvec` "remembers" the original orientation of the slice! This is important