This CNN is to recognize the Captcha of Tencent QQ zone
and is improved based on https://github.com/bojone/n2n-ocr-for-qqcaptcha/blob/master/qqcaptcha-with-xception.py
In order to speed up, we adopt MobileNet instead of Xception.
A pretrained model is available on: https://drive.google.com/file/d/1vc2uI3mf-cJwqyoVc-VLjzhv1QmNSZAd/view?usp=sharing
MobileNets: Efficient Convolutional Neural Networks for Mobile Vision Applications