measure.regionprops_table missing num_pixels as a property in stable

[rsmaior]

Description:

Reading the stable documentation here: https://scikit-image.org/docs/stable/api/skimage.measure.html#skimage.measure.regionprops

We have:

num_pixels: int
Number of foreground pixels.

But whe trying to use that property I get errors.

Way to reproduce:

Example code:

import math
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd

from skimage.draw import ellipse
from skimage.measure import label, regionprops, regionprops_table
from skimage.transform import rotate


image = np.zeros((600, 600))

rr, cc = ellipse(300, 350, 100, 220)
image[rr, cc] = 1

image = rotate(image, angle=15, order=0)

rr, cc = ellipse(100, 100, 60, 50)
image[rr, cc] = 1

label_img = label(image)
regions = regionprops(label_img)

props = regionprops_table(label_img, properties=('area', 'num_pixels', 'slice'))

And the generated error:

  Cell In[47], line 14
    props = regionprops_table(label_img, properties=('area', 'num_pixels', 'slice'))

  File ~\anaconda3\envs\ai\lib\site-packages\skimage\measure\_regionprops.py:1045 in regionprops_table
    return _props_to_dict(

  File ~\anaconda3\envs\ai\lib\site-packages\skimage\measure\_regionprops.py:841 in _props_to_dict
    func = r._extra_properties[prop]

KeyError: 'num_pixels'

Version information:

3.9.16 (main, Mar  8 2023, 10:39:24) [MSC v.1916 64 bit (AMD64)]
Windows-10-10.0.19045-SP0
scikit-image version: 0.20.0
numpy version: 1.24.3

Related issues

There's an older related issue here, but it was not valid since in that time num_pixels were only in the unstable scikit #6337

[jni]

Oops! Thanks for the report @rsmaior! When fixing and writing a test for the fix, I actually caught another missing property. So, thank you for helping us find these! Fix in #7039.