pyvww

Visual Wake Words Dataset

Python library to work with the Visual Wake Words Dataset, comparable to pycococools for the COCO dataset.

pyvww.utils.VisualWakeWords inherits from pycocotools.coco.COCO and can be used in an similar fashion.

pyvww.pytorch.VisualWakeWordsClassification is a pytorch Dataset which can be used like any image classification dataset.

Installation

The code is implemented in Python 3.7 and can be installed with pip:

pip install pyvww

Usage

The Visual Wake Words Dataset is derived from the publicly available COCO dataset. To download the COCO dataset use the script download_coco.sh

bash scripts/download_mscoco.sh path-to-COCO-dataset year

Where year is an optional argument that can be either 2014 (default) or 2017.

The Visual Wake Words Dataset evaluates the accuracy on the minival image ids, and for training uses the remaining 115k images of the COCO training/validation dataset.

To create COCO annotation files that converts the 2014 or 2017 split to the minival split use: scripts/create_coco_train_minival_split.py

TRAIN_ANNOTATIONS_FILE="path-to-mscoco-dataset/annotations/instances_train2014.json"
VAL_ANNOTATIONS_FILE="path-to-mscoco-dataset/annotations/instances_val2014.json"
DIR="path-to-mscoco-dataset/annotations/"
python scripts/create_coco_train_minival_split.py \
  --train_annotations_file="${TRAIN_ANNOTATIONS_FILE}" \
  --val_annotations_file="${VAL_ANNOTATIONS_FILE}" \
--output_dir="${DIR}"

(2014 can be replaced by 2017 if you downloaded the 2017 dataset)

The process of creating the Visual Wake Words dataset from COCO dataset is as follows. Each image is assigned a label 1 or 0. The label 1 is assigned as long as it has at least one bounding box corresponding to the object of interest (e.g. person) with the box area greater than a certain threshold (e.g. 0.5% of the image area).

To generate the new annotations, use the script scripts/create_visualwakewords_annotations.py.

MAXITRAIN_ANNOTATIONS_FILE="path-to-mscoco-dataset/annotations/instances_maxitrain.json"
MINIVAL_ANNOTATIONS_FILE="path-to-mscoco-dataset/annotations/instances_minival.json"
VWW_OUTPUT_DIR="new-path-to-visualwakewords-dataset/annotations/"
python scripts/create_visualwakewords_annotations.py \
  --train_annotations_file="${MAXITRAIN_ANNOTATIONS_FILE}" \
  --val_annotations_file="${MINIVAL_ANNOTATIONS_FILE}" \
  --output_dir="${VWW_OUTPUT_DIR}" \
  --threshold=0.005 \
  --foreground_class='person'

The generated annotations follow the COCO Data format.

{
  "info" : info, 
  "images" : [image], 
  "annotations" : [annotation], 
  "licenses" : [license],
}

info{
  "year" : int, 
  "version" : str, 
  "description" : str, 
  "url" : str, 
}

image{
  "id" : int, 
  "width" : int, 
  "height" : int, 
  "file_name" : str, 
  "license" : int, 
  "flickr_url" : str, 
  "coco_url" : str, 
  "date_captured" : datetime,
}

license{
  "id" : int, 
  "name" : str, 
  "url" : str,
}

annotation{
  "id" : int, 
  "image_id" : int, 
  "category_id" : int, 
  "area" : float, 
  "bbox" : [x,y,width,height], 
  "iscrowd" : 0 or 1,
}

Pytorch Dataset

The pyvww.pytorch.VisualWakeWordsClassification can be used in pytorch like any other pytorch image classification dataset such as MNIST or ImageNet.

import torch
import pyvww

train_dataset = pyvww.pytorch.VisualWakeWordsClassification(root="path-to-mscoco-dataset/all", 
                    annFile=".../visualwakewords/annotations/instances_train.json")