cmapy 0.4

Use Matplotlib colormaps with OpenCV in Python.

cmapy

Use Matplotlib colormaps with OpenCV in Python.

Matplotlib provides a lot of nice colormaps. Cmapy exposes these colormaps as lists of colors that can be used with OpenCV to colorize images or for other drawing tasks in Python.

Original image
viridis

See all of the available colormaps as of Matplotlib 2.2.3 in this all colormaps example.

Requirements

• Python 2.7 or 3.
• Matplotlib.
• OpenCV >= 3.3.0 (to use cv2.applyColorMap()).

Installation

Python 2.7, with pip:

pip install cmapy

Python 3.x, with pip:

pip3 install cmapy

Or, in a Conda environment:

conda install -c conda-forge cmapy 

How to use

Colorize images

Colorize means to apply a colormap to an image. This is done by getting the colormap with cmapy.cmap() and then applying cv2.applyColorMap(), like this:

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

Alternatively, you can use cmapy.colorize() directly:

img_colorized = cmapy.colorize(img, 'viridis')

See the full colorize example.

Draw with colors

Use the cmapy.color() function and an index between 0 and 255 to get a color from a colormap. Cmapy.color() returns a list of BGR (or RGB) values that can be used with OpenCV drawing functions.

# Get color in BGR order (default) by index.
bgr_color = cmapy.color('viridis', 127)

# Get color in RGB order with a float value.
rgb_color = cmapy.color('viridis', 0.5, rgb_order=True)

See a complete drawing with colors example.