How to make a circular color gradient in Python

A color gradient is a way to subtly switch between two or more colors. The term refers to a particular color gradient alternating between colors in a circular pattern, usually beginning with one color in the center and gradually moving to others as you move outward.

Python's circular color gradient function can be a helpful tool for data visualization or for enhancing a project's visual appeal. The Python Imaging Library (PIL) and matplotlib libraries are two of the more popular ways to make a circular color gradient in Python. Both options will be discussed in this Answer, along with examples.

Create a circular color gradient using Matplotlib

Given that matplotlib is a powerful and effective data visualization library in Python and offers numerous ways to create various types of plots, including circular color gradients, it is a common choice among Python programmers to create circular color gradients.

We'll use numpy and matplotlib to create a color gradient by defining a color map.

Example

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.colors import LinearSegmentedColormap
# defining the color map
cmap_colors = [(1, 0, 0), (1, 1, 0), (0, 1, 0), (0, 1, 1), (0, 0, 1), (1, 0, 1), (1, 0, 0)]
colormap = LinearSegmentedColormap.from_list("my_cmap", cmap_colors)
# creating the meshgrid
A, B = np.meshgrid(np.linspace(-1,1,100), np.linspace(-1,1,100))
C = np.sqrt(A**2 + B**2)
# plotting the color map
plt.figure(figsize=(7,7))
plt.pcolormesh(A, B, C, cmap=colormap)
plt.axis("equal")
plt.show()
print("Circular gradient created successfully!")

Explanation

Line 1: We import numpy with an alias np.
Line 2: We import matplotlib with an alias plt.
Line 3: Import the LinearSegmentedColormap, a colormap object based on linear segment lookup tables.
Line 6: We create a list of colors, with each color within a tuple and following the RGB format. The colors are assigned to the variable cmap_colors.
Line 7: The cmap_colors is passed into the LinearSegmentedColormap.
Line 10: We make a rectangular grid out of two given one-dimensional arrays of numbers that are evenly spaced over a predetermined range using the meshgrid() function.
Line 11: The two one-dimensional array is raised to the power of two, added and then the square root is assigned to a variable C.
Line 14: Using the matplotlib alias plt, we determine the size of the plot.
Line 15: With the pcolormesh() we can create 2D image-style plots, passing the variables A, B, C and the colormap into it.
Line 16: This ensures that the axes are equal.
Line 17: We show our color gradient using the .show() method.
Line 18: This is a confirmation message.

Create a circular color gradient using PIL

Another well-liked option for Python image manipulation is the PIL library. We can create a new image and then use the ImageDraw module to draw a circular color gradient using PIL.

Example

from PIL import Image, ImageDraw
#create an image with a white background
image = Image.new("RGB", (200,200), (255, 255, 255))
#create a draw object
obj = ImageDraw.Draw(image)
#define the starting and ending angles for the pie slice
start = 0
end = 90
#define the color gradient
color_gradient = [(255,0,0), (0,255,0), (0,0,255)]
#draw the pie slice with the color gradient
for i, color in enumerate(color_gradient):
    obj.pieslice([25, 25, 175, 175], fill=color, start=start, end=end)
    start += 90
    end += 90
    
#show the image
image.show()

Explanation

Line 1: Import the Image and ImageDraw module from PIL.
Line 3: Create a new image with a white background.
Line 6: Create the draw object.
Line 9: Define the starting angle of the pie slice.
Line 10: The ending angle of the pie slice is defined.
Line 13: We defined the color gradient with three colors in RGB.
Line 16: Loop through the color gradient, the color_gradient variable is converted to an enumerate object.
Line 17: The obj.pieslice() takes four aruguments.
Line 18: Increment the starting angle by $90$ .
Line 19: We also increment the ending angle by $90$ .
Line 22: This shows our PIL image.

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How to make a circular color gradient in Python

Create a circular color gradient using Matplotlib

Example

Explanation

Create a circular color gradient using PIL

Example

Explanation

Conclusion