json_to_dataset fails if image is mono 16-bit

[Kees-van-der-Oord]

Provide environment information

with latest labelme_json_to_dataset.py script and the .exe as well

What OS are you using?

windows 10

Describe the Bug

script fails with 'data type must be np.uint8'
the problem is solved by adding this code before label2rgb():

import numpy as np

img = imgviz.asgray(img)

asgray does NOT convert mono (gray) 16-bits to 8-bits

so do it here:

if img.dtype != np.uint8:
    img =  (img/(np.max(img)/256)).astype('uint8')

lbl_viz = imgviz.label2rgb(
    lbl, img, label_names=label_names, loc="rb"
)

Expected Behavior

the script should be able to handle mono 16-bit images

To Reproduce

run the script with a json file with a 16-bit image