Apply MatplotLib or custom colormap to OpenCV image

Question

OpenCV has a limited amount of color maps. MatplotLib has many more color maps, but it is not straightforward to apply these colormaps to given OpenCV images. How to apply MatplotLib color maps from the page below to OpenCV images when using the Python API? This is similar to applying a custom colormap to a given image.

https://matplotlib.org/examples/color/colormaps_reference.html

Answer 1

For Python >= 2.7, cmapy packages this functionality in a convenient way. Install it with:

Python 2.7:

pip install cmapy

Python 3.x:

pip3 install cmapy

Or, for Anaconda (from conda-forge):

conda install -c conda-forge cmapy 

And use it like this:

import cv2
import matplotlib.pyplot as plt
import cmapy

# Read image.
img = cv2.imread('imgs/woman.png')

# Colorize.
img_colorized = cv2.applyColorMap(img, cmapy.cmap('viridis'))

# Display
plt.imshow(img_colorized)
plt.show()

Different colormaps give something like this:

See all the available colormaps in action here.

Disclaimer: I wrote cmapy (because I needed this functionality for another project), and internally, it does pretty much the same as the other answers.