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End-to-End Recognition of Handwritten Notes in Scanned Documents

This repository contains all files necessary to train, run, and evaluate the sytem presented in the Master's Thesis "End-to-End Recognition of Handwritten Notes in Scanned Documents". With the end-to-end system, you can transcribe (only the) handwritten notes on pages, even when they are mixing with printed text. This repository does not include any models; however you can download some here or train them yourself.

A good dataset to train the model on is the Paper Notes dataset.

In the following, the Training, Running, Evaluation (with Ceiling Analysis) is described.

Setup

The system was implemented using Tensorflow 1.9, Python 3.7, CUDA 10, and cuDNN 7.4. All networks were evaluated on a system with a GeForce GTX 1080 Ti GPU with about 11 GB of memory, an Intel i9-7900X CPU with 3.3 GHz, and about 64 GB of RAM.

To install the dependencies, run pip install -r requirements.txt. There might be some missing even though I tried to keep the file complete.

Training

The system is made up of several building blocks, which can be combined together:

In this section, training the deep learning components (i.e. Text Separation, Text Classification, Text Recognition) as well as setting up the Language Model is described.

Gathering the data

First you should download the IAM dataset. For this, run

python -m data.download --dataset iam --user USERNAME --pwd PASSWORD

PASSWORD and USERNAME should be replaced with the respective values you set up to access the IAM database.

Next, you need to prepare the datasets for training. This can be done with

python -m data.prepare --config iam-both-small

The config parameter tells the program what configuration to consult. There are two configurations provided: iam-both-small and iam-both-large. You can create your own configurations by placing a .json file in the /data/config/ folder.

If you want to base the splitting into train, test, dev on the Paper Notes dataset, you should run it with the following command. Here, you of course should adjust the path yourself to the according folder.

python -m data.prepare --config iam-both-small --split ../paper-notes/data/final

The following options are available:

{
  "dataset": "iam", // The base dataset
  "subset": "both", // Which subset to use. "both" describes words and lines for iam
  "limit": -1, // Limit of samples (-1 is infinite)
  "shuffle": true, // Whether or not to shuffle
  "test_frac": 0.1, // Fraction for testing
  "dev_frac": 0.1, // Fraction for development
  "invert": true, // Whether to invert the files
  "threshold": false, // Whether to apply thresholding
  "crop": true, // Whether to crop the image to the smallest part of non-background pixels
  "scale": {
    "mode": "none" // How to scale the image. Modes are "factor",
    //"none", "height", "line" (see scale.py for more detail)
  },
  "padding": 5, // Number of pixels to padd with
  "binarize": false, // Whether to binarize
  "printed": {
    // If this option is included you add printed text versions
    "minlength": 2, // Minimum length of text to make it printed
    "count": [10000, 1000, 1000], // Number of samples per [train, dev, test]
    "padding": 5, // Padding to apply
    "printing_padding": 5, // padding of the printed text
    "crop": true, // Whether to crop the printed text
    "height": {
      "min": 10, // Minimum height
      "max": 110, // Maximum heihgt
      "center": [20, 40, 60, 80, 100], // Centers of gaussian distributions for random height selection
      "scale": 5
    },
    "foreground": {
      "low": 0, // The values the foreground pixels can be betrween
      "high": 0
    },
    "filters": [],
    "fonts": [
      // Which fonts to use
      "./data/fonts/AppleGaramond.ttf",
      "./data/fonts/Cursif.ttf",
      "./data/fonts/EnglishTowne.ttf",
      "./data/fonts/LinLibertine.ttf",
      "./data/fonts/OldNewspaperTypes.ttf",
      "./data/fonts/Roboto-Light.ttf",
      "./data/fonts/Asar-Regular.ttf",
      "./data/fonts/Bellefair-Regular.ttf",
      "./data/fonts/JosefinSlab-Thin.ttf",
      "./data/fonts/JosefinSlab-Light.ttf",
      "./data/fonts/Lato-LightItalic.ttf",
      "./data/fonts/Lato-Hairline.ttf",
      "./data/fonts/LibreBaskerville-Italic.ttf",
      "./data/fonts/LibreBaskerville-Regular.ttf",
      "./data/fonts/PlayfairDisplay-BoldItalic.ttf",
      "./data/fonts/PlayfairDisplay-Regular.ttf",
      "./data/fonts/Tangerine-Regular.ttf",
      "./data/fonts/TulpenOne-Regular.ttf",
      "./data/fonts/Ubuntu-MediumItalic.ttf",
      "./data/fonts/IMFeENsc28P.ttf"
    ]
  }
}

Text Separation

To train the Text Separation Network, you first need to define a configuration file. In my thesis, I used config/separation/base.json. Here are some of the options.

{
  "name": "separation", // name of the configuration
  "save": 2, // after which epoch to make a checkpoint (here, every second epoch)
  "binary": true, // Whether to binarize the data
  "max_batches": {
    "sep": {
      // MAximum number of batches per subset
      "train": 1000,
      "val": 1000 // same as "dev"
    }
  },
  "data_config": {
    "paper_note_path": "../paper-notes/data/final", // Path to the paper notes dataset
    // How the page should be separated into tiles/slices
    "slice_width": 512,
    "slice_height": 512,
    "filter": true, // Whether to filter out slices without handwriting
    "otf_augmentations": {} // see data/ImageAugmenter.py for options
    // empty object means no augmentations are applied
    // otf stands for "on the fly", thus there will be no two batches alike
  },
  "batch": 4, // Size of a batch
  "learning_rate": 0.0000001, // Size of the learning rate
  "algo_config": {
    "filter_size": 5, // Filter size of the convolutions
    "features_root": 32, // Number of features in the first convolution (doubled every contracting block)
    "batch_norm": false, // whether to use batch norm
    "group_norm": 32 // whether to use group norm and the group size
    // ...  more options can be found in ./nn/tfunet.py
  }
}

To start the actual training, execute

python train_separation.py --config base [--gpu GPU_INDEX] [--model-date] [--model-epoch]

You should pass a GPU parameter with the index of the GPU to use. Default is -1, thus CPU execution. The model snapshots are stored in models/$NAME_OF_THE_CONFIG_$CURRENT_DATE/. Therefore, if you want to continue training an existing model, you should pass --model-date set to the according date and --model-epoch to the epoch where you want to continue. Of course, you can replace base with whatever configuration you want to use (in the same schema, without the config/separation folder name and without .json).

Text Classification & Recognition

Training the text classification and recognition network are very similar to the text separation network. Since they are interleaved as multi-task learning networks, they are both trained at once. The configuration used in my thesis is config/otf-iam-paper-fair.json.

The Text Recognition Network is based on Joan Puigcerver's

The following options in the configuration are available:

{
  "name": "otf-iam-paper", // name of the configuration
  "dataset": "iam-both-small", // which dataset to use (go by filename)
  "algorithm": "htrnet", // You should stick to this
  "save": 3, // After which epoch to create a snapshot of the model
  "batch": 50, // Batch size
  "epochs": 1000, // number of epochs
  "max_batches": {
    "rec": {
      "train": 400, // numberof batches for recognition training
      "dev": 200 // number of batches for recognition validation
    },
    "class": {
      "train": 300, // number of batches for classification training
      "dev": 100 // number of batches for classificaiton development
    }
  },
  "learning_rate": 0.0003, // Learning reate for recognition
  "class_learning_rate": 0.0001, // Learning rate for classification
  "ctc": "greedy", // Which decoder to use for ctc
  "data_config": {
    "shuffle_epoch": true,
    "type_probs": {
      // Probability to select a given subset
      // This should be chosen according to the amount of words/lines
      // In this case, it yields roughly 50-50 in the training
      "lines": 1,
      "words": 0.12
    },
    "otf_augmentations": {
      // similar to text separation
      "affine": {}, // empty object here means that the standard settings from data/steps/pipes/affine.py
      "warp": {
        "prob": 0.5,
        "deviation": 1.35,
        "gridsize": [15, 15]
      }
    },
    "preprocess": {
      // Which preprocessing steps to apply with
      "crop": true,
      "invert": true,
      "scale": 2.15,
      "padding": 5
    },
    "postprocess": {
      // This is not applied after the training, but after preprocessing & augmentation
      "binarize": true
    }
  },
  "algo_config": {
    // Settings for the algorithm itself
    "format": "nchw",
    "scale": false,
    "encoder": {
      "type": "cnn",
      "cnn": {
        "bias": true,
        "dropout": {
          "active": true
        },
        "bnorm": {
          "active": true,
          "train": true
        }
      }
    },
    "classifier": {
      "units": [512] // which dense layers are added
    },
    "fc": {
      "use_activation": false
    },
    "optimizer": "adam"
  }
}

To start the actual training, execute

python train.py --config otf-iam-paper-fair [--gpu GPU_INDEX] [--model-date] [--model-epoch] [--no-trains] [--no-class] [--paper-notes] [--only-paper]

The config, gpu, model date and model epoch are similar to the text separation network. With --no-trans and --no-class you can skip training on either the recognizer or the classification part. With --paper-notes, you can add training on the extracted words of the Paper Notes dataset. With --only-paper, the models are only trained on the Paper Notes dataset. With the Paper Note options, you should also set --paper-note-path to the acording path if it deviates from ../paper-notes/data/words

Language Model

To create the language model, you need to download and place the brown / lob corpus in the folder data/raw/corpus. If you want to train on other files, you should check out build_corpus.py to see what's necessary (also if you want to adjust the path to the paper notes, which causes some words to be removed that are appearing in the evaluation/testing data).

Run the following to create the corpus then:

python build_corpus.py

The corpus is then created as ./data/output/corpus.json. However, the corpus used in my thesis is also commited as data/corpus.json (this is the location where the Language Model will look for the corpus, so either replace that file or change the language model settings).

Word Detector, Paragraph Detector, Line Segmentation & Co

These models are currently trained by simply evaluation every parameter (see in the evaluation section below).

Running

Single Building Blocks

You can run the classifier, recognition network and separation network by themselve.

To run the text recognition network, use the following command:

python transcribe.py --gpu GPU_INDEX --config THE_CONFIGURATION_THAT_YOU_USED --model-date DATE_OF_MODEL --model-epoch MODEL_EPOCH --dataset DATASET

For the classification network, run this:

python runclass.py --gpu GPU_INDEX --config THE_CONFIGURATION_THAT_YOU_USED --model-date DATE_OF_MODEL --model-epoch MODEL_EPOCH --dataset DATASET

In all of these comands, you should replace the arguments accordingly:

  • --gpu either -1 for CPU or the gpu index
  • --config Which config you used to train the model
  • --model-date The date of the model (i.e. what it says in the folder name)
  • --model-epch The epoch you want to use
  • --dataset The dataset to use for running - e.g. iam-both-small

For the separation network, the parameters have the same meaning but are a bit less. You should only add --paper-note-path if the path deviates from ../paper-notes/data/final.

python run_separation.py --gpu GPU_INDEX --model-date MODEL_DATE --model-epoch MODEL_EPOCH [--paper-note-path PATH_TO_PAPER_NOTES_FOLDER]

You will find the ouput in the predictions folder.

The whole pipeline

Running the whole pipeline is based on configurations you can use for the end-to-end settting. This is the command to run a configuration:

python e2e.py --gpu GPU_INDEX --config CONFIGURATION

The --config parameter is relative to the ./config/e2e folder. The best results yielded the sep-line-class-lm and the sep-line-class configuration.

This is what a typical configuration for running looks like:

{
  "blocks": [
    // The building blocks in their order
    {
      "type": "..."
      //...
    },
    {
      // ...
    }
    // ...
  ],
  "data": [
    // Either an array of file paths or a link to a Paper Notes dataset.
    // The latter is described further below
  ],
  "viz": {
    // You can add the "viz" option if you want to output the results
    "type": "RegionVisualizer",
    "store": "./e2eoutputs/wpi",
    "large": true
  }
}

Further configuration options are listed in Evaluation and Ceiling Analysis.

Blocks

The blocks section is where the actual magic happens and you list the blocks that you want to use (and in which order). A block looks like this:

{
    "type": "The Type of the Block",
    "disabled": true | false,
    // ... Block specific configuration...
},
Text Separation Block
{
    "type": "TextSeparation",
    "disabled": false,
    // Path to the model
    "model_path": "./models/separation-2018-10-10-17-58-01",
    // Epoch to the model
    "model_epoch": 19,
    //
    "binarize_method": "mean_threshold" | "fast_threshold" | "sauvola"
},

fast_threshold is setting the threshold to 254. This is only working when your background is perfectly white.

Word Detector
{
    "type": "WordDetection",
    // Configuration for the detector
    "extractor": {
        "cluster_y_eps": 0.06,
        "cluster_x_eps": 0.54
    }
},
Paragraph Detector
{
    "type": "ParagraphDetection",
    // settings for the detector
    "extractor": {
        // Kernel of the sauvila filter
        "sauvola_window": 19,
        // Kernels for the erode and dilate operation
        "erode_kernel": [35, 35],
        "dilate_kernel": [35, 35],
        // How much smaller you want to process the image
        "scaling": 5,
    }
},
Line Segmentation Algorithm
{
    "type": "LineSegmentation",
    // Settings for the segmenting algorithm
    "extractor": {
        // How much smaller you want to process the image
        "scale_factor": 5.0,
        "erode_kernel": [1, 10],
        "dilate_kernel": [1, 10],
        // Distance between two local maxima
        "relative_maxima_dist": 35,
        // Settings for the A* Line Segmentation Algorithm
        "astar": {
            "c": {
            "d": 60,
            "d2": 0,
            "m": 275,
            "v": 3.5,
            "n": 1
            }
        }
    }
},

The configuration A* Line Segmentation Algorithm is described well in the paper it is stemming from.

Text Recogniton and Classification
{
  "type": "TranscriptionAndClassification",
  // PAth to the model
  "model_path": "./models/otf-iam-paper-2018-10-30-13-33-59",
  // Epoch of the model
  "model_epoch": 74,
  // Whether you want to activate classification or not
  "classify": true
}
Language Model

This is the most simple:

{
  "type": "UnigramLanguageModel",
  "source": "Path to the corpus.json"
}

Data

Apart from as an array of files, you can also path an object of settings:

"data": {
    // Folder to check out
    "path": "../paper-notes/data/final/test/",
    // Ending of the files to consider
    "suffix": "-paper.png",
    // Whatever the file name should start with
    "prefix": "...",
    // 0 or smaller means unlimited
    "limit": 100
  }

Evaluation

Single Building Blocks

You can evaluate the Text Recognition, Classification, and Separation Network individually.

For the Text Recognition and Text Classification:

python eval_textrec.py --gpu GPU_INDEX --model-date MODEL_DATE --model-epoch MODEL_EPOCH [--paper-note-path PATH_TO_PAPER_NOTES]

For Text Separation:

python eval_sep.py --gpu GPU_INDEX --model-date MODEL_DATE --model-epoch MODEL_EPOCH [--paper-note-path PATH_TO_PAPER_NOTES]

See the Training section to see what these arguments should contain.

End-to-End pipeline

Evaluating the full pipeline is very similar to running it. To add a validation mode, you should add the following fields to the main object:

// This is the ground-truth you will rely on.
// You can choose between LineRegion (i.e. Lines),
// WordRegion and ParagraphRegion.
// This is heavily biased towards the Paper Notes dataset,
// i.e. the -paper.png or -stripped.png suffix is replaced by  -truth.json
// to get the ground truth.
  "gt": {
    "type": "LineRegion",
    // Whether the ground truth should be visualized as well (if you have a viz field in the main object)
    "viz": false
  },
  "eval": [
      // Which evaluation metrics you want to run.
      // You can use IoU, IoUCER (mix of IoU and CER), IoUPixelSum
      // (sum of pixel values of one region compared to the sum of pixel values from another)
      // And the Bag of Words score
    {
      "type": "IoUCER",
      // Filter class should be set to true if you perfrom the text classification. This is valid for all scores
      "filter_class": true,
      // Which treshold to use for IoU matching (standard is often 0.5 but here set to 0)
      "threshold": 0,
      // name for this score. This is IOUCER specific
      "name": "ioucer_0"
    },
    {
        "type": "IoU",
        "threshold": 0.5,
        "filter_class": false
    },
    {
      "type": "IoUPixelSum",
      "threshold": 0,
      "filter_class": false,
      // Whether to binarize the image first
      "binary": false
    },
    {
      "type": "BagOfWords",
      "filter_class": true,
      // Punctuations are disregarded
      "punctuation": ",.;:!?",
      // How words are separated
      "split": "|"
    }
  ],

Evaluating several hyperparameters

If you want to evaluate more than just one configuration without having to manually edit them, you can the following field to flexibly adjust the options:

// The "ranter" cares about evaluating multiple ranges
"ranger": {
    // The path to the field you want to alter
    // You can also specifiy multiple paths, but they will all receive the same value
    "paths": [["eval", 0, "binary"]],
    // The range of values
    "values": {
      "from": 0,
      "to": 2,
      "step": 1
    },
    // This is for the logger, it will use the template to name the current execution accordingly. {} is replaced by the current value
    "template": "binary {}"
  }

Ceiling Analysis

Performing the ceiling analysis is also done by altering the end-to-end configuration. This is now done in the blocks field. Simply pass the following as the first block and adjust it according to the building block you want to replace:

{
    "type": "Ceiling",
    // This accepts the same as the GtProvider
    "provider": "LineRegion"
},

Available end-to-end configurations

There are a couple of end-to-end configurations available by default. These are grouped into:

  • /config/e2e/ceiling - Configurations for Ceiling Analysis
  • /config/e2e/final - Different combinations of the building blocks
  • /config/e2e/steps - Step-by-step of one configuration
  • /config/e2e/wpi.json - Configuration to run on Examples of the WPI

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End-to-End Recognition of Handwritten Notes in Scanned Documents

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