CODEWITHSUNDEEP
pythonmatplotlib
tillsten
tillsten

Reputation: 14878

How to place an external image on a figure with fixed, dpi-independent size?

As written in the question title, I want to be able to place an image on the figure with the images size given in inches.

Upvotes: 0

Views: 123

Answers (1)

Ajean
Ajean

Reputation: 5659

Perhaps figimage will work for you? You just have to account for the figure dpi and reshape your image accordingly. I wrote a short placement routine that should size it right, using a RectBiVariateSpline for the interpolation:

import matplotlib.pyplot as plt
import numpy as np
from scipy.interpolate import RectBivariateSpline

def place_img_on_fig(fig, img, size_inches):

    # Figure out the right size
    dpi = fig.dpi
    new_pxsize = [i * dpi for i in size_inches]

    # Interpolate to the right size
    spline = RectBivariateSpline(np.arange(img.shape[0]),
                                 np.arange(img.shape[1]),
                                 img)
    newx = np.arange(new_pxsize[0]) * (np.float(img.shape[0]) / new_pxsize[0])
    newy = np.arange(new_pxsize[1]) * (np.float(img.shape[1]) / new_pxsize[1])
    new_img = spline(newx, newy)

    # Call to figimage
    fig.figimage(new_img, cmap='jet')

# Make the figure
fig = plt.figure(figsize=(5,1), dpi=plt.rcParams['savefig.dpi'])

# Make a test image (100,100)
xx, yy = np.mgrid[0:100,0:100]
img = xx * yy

# Place the image
place_img_on_fig(fig, img, (0.5,4))

plt.show()

This places the 100x100 image on the figure like it is 0.5 inches high and 4 inches wide. You can add offsets to the figimage call if you so desire. long thin image

Upvotes: 1

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