CAPTCHA_IND

This is a tool to identify CAPTCHA basing on CNN implemented by mxnet. Each CAPTCHA consists of 4 letters or digits. Neither upper case nor lower case is considered when it comes to the letters in CAPTCHA.

The cnn model should be trained before taken into use.

1. Get the training datasets

If you would like to download and construct the datasets from the very beginning, just remove my datasets directory and run the get_datasets.sh script:

    $ cd CAPTCHA_IND 
    $ sh scripts/clear.sh data
    $ sh scripts/get_datasets.sh

This may take a long time to download. Otherwise, you may simply use the datasets I downloaded and constructed for you by skipping this step.

2. A bit setup

So as to install some necessary packages, just execute the setup.sh script:

    $ sh scripts/setup.sh

3. Train the model

To train the model, run the train.py script:

    $ python train.py

This will train the model with datasets downloaded in step 1. Besides, the trained model will be exported and saved to the directory model_export. If one would like to remove the model saved before, he or she could run the script clear.sh like this:

    $ sh scripts/clear.sh model

4. Test

After training, one could test the trained model by running the script:

    $ python test.py

This will choose a small batch data from the test dataset and feed it to the model. The predicted captcha together with the correct captcha will be printed to the terminal for comparing.

5. Random search hyper parameters

A python script is provided to search the hyper parameters of learning_rate, learning_rate_factor (let lr decay each 500 iterations) together with the weight decay (L2 regularization). Run the python script and a log file will be generated in the current directory which records the model hyper parameters and their associating validation accuracy.

    $ python random_search_hypers.py