Py2NiiVueColormaps

The purpose of the repository is to generate additionalcolormaps for NiiVue. NiiVue comes with many built-in colormaps, which you can explore in this live demo.

The live demo custom button also shows how you can define new colormaps:

let cmap = {
  R: [0, 255, 22, 127],
  G: [0, 20, 192, 187],
  B: [0, 152, 80, 255],
  A: [0, 255, 255, 255],
  I: [0, 22, 222, 255],
};
let key = "Custom";
nv1.addColormap(key, cmap);
nv1.volumes[0].colormap = key;

Generating matplotlib colormaps

matplotlib provides many of its own colormaps. The purpose of this repository is to convert many of the matplotlib _cm.py colormaps to NiiVue's JSON format. To re-build the colormaps in the lut folder you can run:

git clone https://github.com/niivue/Py2NiiVueColormaps
cd Py2NiiVueColormaps
python lut2niivue.py

Note that _cm.py uses several different methods to colormaps, and this repository only currently converts some of these (it generates a report of the converted and skipped colormaps). Note that the file _cm.py is from matplotlib and retains that permissive license.

Generating scientific colormaps

The scientific colormaps for Python project provides many colormaps that you can view on their catalog web page.

Here we provide a script to convert these to NiiVue format. For example, to convert the davos colormap:

git clone https://github.com/niivue/Py2NiiVueColormaps
cd Py2NiiVueColormaps
pip install cmap
python color2clut.py davos

Run python color2clut.py without arguments to batch-convert a default set of colormaps. The optional -t argument sets the interpolation tolerance, letting you balance node count against color precision.