hetsch hetsch - 2 months ago 8
Python Question

Two dimensional color ramp (256x256 matrix) interpolated from 4 corner colors

What I want to achieve is to programmatically create a two-dimensional color ramp represented by a 256x256 matrix of color values. The expected result can be seen in the attached image. What I have for a starting point are the 4 corner colors of the matrix from which the remaining 254 colors inbetween should be interpolated. While I had some success for interpolating the colors for one axis, the two-dimensional calculation provides me some bad headaches. While the image seems to have a non-linear color gradient, I would be happy with a linear one.

If you could give me some hints how to do this with numpy or other tools I`ll be more than thankful.

enter image description here

Answer

Here's a super short solution using the zoom function from scipy.ndimage. I define a 2x2 RGB image with the intial colors (here random ones) and simply zoom it to 256x256, order=1 makes the interpolation linear. Here is the code :

import numpy as np
import matplotlib.pyplot as plt 

im=(np.random.rand(2,2,3)*255).astype(np.uint8)

from scipy.ndimage.interpolation import zoom
zoomed=zoom(im,(128,128,1),order=1)

plt.subplot(121)
plt.imshow(im,interpolation='nearest')
plt.subplot(122)
plt.imshow(zoomed,interpolation='nearest')
plt.show()

Output:

output from the script