Character Recognition

Estimated time: 15 minutes

In this part of our introduction you will learn how to:

  • upload your data to the cloud storage;
  • use image channels;
  • use Jupyter notebooks running in cloud from within Neptune UI;
  • compare your models within the Experiment List.

Let’s move on to a more realistic example - classification of letters from the notMNIST dataset using artificial neural networks. We will use Keras, a popular library for deep learning. Since we’ll work entirely in the cloud, there is no need to install anything.

Begin by entering the example’s directory:

cd ../2-character-recognition

Data Upload

We now need to deliver our dataset to Neptune.


Store your datasets outside of experiment’s directory.

Every time you run an experiment, Neptune uploads your code to the cloud and you usually don’t want the dataset to be a part of that upload.

The dataset is included in the neptune-examples repository. Upload it to your Neptune cloud storage using the following command (it assumes you’re in the experiment’s directory):

neptune data upload ../data/notMNIST_small.mat

Training the Model

Our implementation in the file uses Keras library and requires a GPU to run.

With Neptune you can easily specify a type of machine to run the experiment on and the compute environment (Docker image) for your code:

neptune send \
  --environment keras-2.2-gpu \
  --worker s-k80 \
  --input notMNIST_small.mat

Now let’s focus on the training process. You will see a typical learning curve: accuracy and log-loss, both for training and validation.

charts screenshot

Sometimes a more fine-grained inspection is helpful to learn what is and what isn’t working. Neptune allows you to look at misclassified letters - just open the Channels tab in the left panel.

What you’re seeing is an image channel. In the previous examples, you sent numerical values to Neptune. You can, just as easily, send images to Neptune UI from your python code. Look how it is done in

ctx.channel_send('false_predictions', neptune.Image(
  name='my image',
  description='this image depicts a cat',
  data=pil_image # an image in PIL format

images channel screenshot

Running Experiments in a Notebook

In addition to experiments started from your console, you can experiment using interactive Jupyter notebooks hosted in the cloud.

Click Start Notebook in the upper left corner of Neptune UI. You’ll be asked to select a worker type (use s-k80) and environment (use keras-2.2). You also need to add notMNIST_small.mat as an input - it will make it accessible from within the notebook. Finally, you can upload a notebook file by clicking Browse and selecting neptune-examples/2-character-recognition/main.ipynb.

starting notebook

Click Start and in a short while your notebook will be up and running.

Fine-Tuning the Algorithm

Deep learning models benefit a lot from architecture and parameter tweaking, so go ahead to the code and uncomment a few commented lines. This will add much-needed complexity to our convolutional network:

code to uncomment

Now, let’s run the experiment pressing CTRL+Enter or clicking Cell -> Run Cells with focus on the cell.

Did you lower the Log-loss validation? You can check it in the Channels tab. And yes, channels do work with notebooks!

Compare Your Experiments

In order to compare multiple experiments Neptune comes with Experiment List view. You can go there by clicking on the up arrow in the upper left corner of Neptune UI.

It is another place where you can use channels. Just select Log-loss validation channel from the Manage columns / Numeric Channels menu on the right.

experiments screenshot

Now you can compare your experiments based on the last value in the channel. Did you make progress?

If you’re done with improving your model, you can move on to the next example: Neural Style Transfer.