Does the Google Mobile Vision (https://developers.google.com/vision/) API work offline? Or does it need Internet connectivity? The sample app does not require any Internet permission. Which means the API works entirely offline. I am looking for a positive confirmation of this.
PS. Also I am looking for more information on this API. For example, does it use neural networks? If so what algorithms were used? I can not find any detail discussion anywhere.
The API does an initial library download the first time that it is used, and then works offline from that point on.
I tried the official sample app here.
I installed the sample app on a device in airplane mode, and continued to run under airplane mode - It works without problem.
(Note that I only tested the OCR part)
But as far as I know, all google services libraries made use of an already installed (On most device, probably, except China models) application named Google Play Services. As long as this application is installed in the device (With a reasonably updated version), the Vision API should works even under no internet connectivity.
来源：https://stackoverflow.com/questions/40832882/does-machine-vision-api-work-offline