Superimpose heatmap on a base image OpenCV Python

Updated Answer — 29th April, 2022.

After the repeated comments I have decided to update this post with a better visualization.

Consider the following image:

img = cv2.imread('image_path')

I obtained a binary image after performing binary threshold on the a-channel of the LAB converted image:

lab = cv2.cvtColor(img, cv2.COLOR_BGR2LAB)
a_component = lab[:,:,1]
th = cv2.threshold(a_component,140,255,cv2.THRESH_BINARY)[1]

Applying Gaussian blur:

blur = cv2.GaussianBlur(th,(13,13), 11)

The resulting heatmap:

heatmap_img = cv2.applyColorMap(blur, cv2.COLORMAP_JET)

Finally, superimposing the heatmap over the original image:

super_imposed_img = cv2.addWeighted(heatmap_img, 0.5, img, 0.5, 0)

Note: You can vary the weight parameters in the function cv2.addWeighted and observe the differences.