Can't recognize an image with only '0'

[gurudk]

import easyocr

reader = easyocr.Reader(['ch_sim', 'en']) # this needs to run only once to load the model into memory
result = reader.readtext('zero.jpg')
print(result)

===========================output=================
[]

[gurudk]

I debug the code , find the defualt text_threshhold = 0.7 is too high.
I set this value to 0.3, that is ok!