TikZ Image Colorbar

This small snippet adds the functionality to place a colorbar besides a TikZ node and hence an image.

In fact it's easier to employ pgfplots capability of producing colorbars and place the image in an axis environment. Also, pgfplots directly supports viridis, which is nice.

Commands

\NodeColorbar

\NodeColorbar adds a colorbar to the node specifyed by the key node. This node should be set anchor=south west (up to now). The Colorbar is then placed besides (left) to the node adopting its height.

Further Keys available

• node name of the node, the colorbar is placed relative to; this argument is mandatory
• position (0.05) position with respect to the right side of the node given in percent of the nodes width, i.e. the standard value leaves 5% between the nodes border and the center of the colorbar
• width (0.025) complete width of the colorbar, i.e. width/2 to the left and right of the position determines the width (hence position-width/2 should be greater than 0)
• colorbar provide your own colorbar manually (you also can add this to the colors key, see next), by specifying each color fading yourself with tuples of two: value/color, where the first value must be 0, the values should be increasing and the last one should be 1. The colors are just xcolors
• colors sets the colorbar key directly with predefined styles, which are up to now
  • gray black (0) to white (1) colorbar
  • hsv the colormap hsv as provided by MatLab, i.e. the hue range of the HSV color space
  • jet the colormap jet provided by MatLab
  • rwb from red (0) to white (0.5) to blue (1)
• y range specify the range of the values the colorsbar indicates, given in the form min to max. Specifying this value activates the short form (see y ticks below)
• y tick at border (false) put ticks at the borders (0,1) of the colorbar. This value only has effect if the short form is activated (see y ticks). If it is false these is half a tick space left at each border
• y ticks There are two possibilities to specify ticks
  1. short form. By specifying y range, this value should be an integer specifying the number of ticks to be used. Together with y tick at border this determines the positions and values of the ticks. Each tick is printed using \pgfmathprintnumber, see their documentation to change the appearance of numbers.
  2. each tick is given as a tuple position/label, where position is relative, i.e. a value in [0,1] and label is a text or math to be displayed at the ticks end. Example: y ticks = {0/{\(pi\)}, 0.5/{\(0\)}, 1/{\(\pi\)}}

\includegraphicsWithColorbar

Combines the \NodeColorbar and provides an interface to directly specify the image to be included. There are 3 Parameters, the first two are optional. The parameters are

1. the keys given to \NodeColorbar (see last section).
2. the keys given to \includegraphics such as width= or height= and is optional similar to the one of the command itself.
3. the path to the image, cf. the second parameter of \includegraphics

Available Styling Arguments

• ICBFrame styling of the frame surrounding the colorbar
• ICBImage in the \includegraphicsWithColorbar, these keys are added to the node containing the image
• ICBLabel styling for the labels at each tick.
• ICBTick styling for the ticks

Limitations & Possible Extensions

• The code was only tested using TikZ 3.0.0
• works up to now only if the node is set anchor=south west
• in certain ranges (i.e. -0.5 to 0.5) there are rounding errors, when specifying an odd number of ticks for the value of 0.
• The Ticks-Type is up to now covering the right half of the colorbar. This could be individualized maybe by drawing the complete line and defining a dash-pattern

License

This small code snipped is published under the Beer/Coffee ware license as proposed by Poul-Henning Kamp.

% THE BEER-WARE LICENSE (Rev. 42):
% Ronny Bergmann <mail@rbergmann.info> wrote this file. As long as
% you retain this notice you can do whatever you want with this stuff. If we
% meet some day, and you think this stuff is worth it, you can buy me a beer
% or coffee in return.