Graphics card over image

Question

I have images of different objects (Pascal Voc), and I have a probability diagram. I want to visualize it by building an image and somehow on top of it. What would be the best way to do this?

I thought about using the alpha channel as follows:

im_heat = np.zeros((image.shape[0],image.shape[1],4))
im_heat[:,:,:3] = image
im_heat[:,:,3] = np.rint(255/heatmap)
plt.imshow(im_heat, cmap='jet')
plt.colorbar()

How to adjust the color panel from min (heatmap) to max (heatmap)? Or is there a better way to visualize probabilities?

Answer 1

matplotlib, , colorbar. contourf, colorbar ( vmin=min(heatmap) vmax=max(heatmap) , ). , ( ). , , :

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors
import Image

#2D Gaussian function
def twoD_Gaussian((x, y), xo, yo, sigma_x, sigma_y):
    a = 1./(2*sigma_x**2) + 1./(2*sigma_y**2)
    c = 1./(2*sigma_x**2) + 1./(2*sigma_y**2)
    g = np.exp( - (a*((x-xo)**2) + c*((y-yo)**2)))
    return g.ravel()


def transparent_cmap(cmap, N=255):
    "Copy colormap and set alpha values"

    mycmap = cmap
    mycmap._init()
    mycmap._lut[:,-1] = np.linspace(0, 0.8, N+4)
    return mycmap


#Use base cmap to create transparent
mycmap = transparent_cmap(plt.cm.Reds)


# Import image and get x and y extents
I = Image.open('./deerback.jpg')
p = np.asarray(I).astype('float')
w, h = I.size
y, x = np.mgrid[0:h, 0:w]

#Plot image and overlay colormap
fig, ax = plt.subplots(1, 1)
ax.imshow(I)
Gauss = twoD_Gaussian((x, y), .5*x.max(), .4*y.max(), .1*x.max(), .1*y.max())
cb = ax.contourf(x, y, Gauss.reshape(x.shape[0], y.shape[1]), 15, cmap=mycmap)
plt.colorbar(cb)
plt.show()

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