Snack Watching with Raspberry Pi

Starting as a fun Jonah Group project, the Snack Watcher is designed to watch the company’s “Snack Table”. If there are some new “Snacks” presented on the “Snack Table”, it can be used to report the event onto chat channels, emails or messages saying “Snack Happened!”, posting an image and trying to classify the snacks that it observed. It supports both as web site for interactive snack viewing and RESTful API for programmatic snack querying.

Snack Watcher Github Repo

  • Webcam connected to watch at the “Snack Table”

Snack Watcher Setup 2

  • snack-web captured image sample with blob status (green means New, red means removed) and blob classification (they looks like “package” from classifier training)

Snack Web Image Capture


snack-web is a web application showing the result of snack watching, which has been designed to configure and run on a Raspberry Pi 2 or 3. snack-web can be driven, either manually (via Web) or programmatically (via RESTful API) to take pictures and push the snapshots into the static/images directory. Alternatively, the RESTful API can be programmatically used to watch and to return the images. The API is a key feature to integrate with a external system, providing utilities to report the snacks status.

snack-web Front Page

The following illustrated the front page of snack-web, the front page menu items are listed:

  • Links: display the last N snack captured image and it’s processing stages
  • Calibrate: take a background image for calibrating the background colour
  • Snap: snap a snack image from the camera now
  • Teach: (Require advanced setup) Currently still under heavy development, the teaching module is designed to interactively classify snack for future training. This required classifier setup to work.

Snack Web Front Page

For each snack image capture, it collects the set of processed images for debugging. User can understand how the snacks are identified. For each blob that the system detected, it is stored for displaying and for training. The colour coded blob represent, green is the new blob, yellow is the stationary blob, and red is the removed blob. By click on each image bar, a larger image is shown for detail inspections.

Snack Web Item Display


http://snack-web:8000/api (Replace snack-web with your host location.)

The images and operations can also be accessed via RESTful API. The available URI resources are listed in this table.

Table: snack-web RESTful API

API HTTP Description
/snacks/ GET return all images, that could be a lot of images
/snacks/snap GET take a snapshot and return the latest image. This call takes a snapshot and returns the processed image.
/snacks/id/{id} GET return image {id}. This call gets an image by the database id. If it is not found, null is returned.
/snacks/state/{class_state} GET Get all blobs matched the given class_state. This call gets a list of blobs filtered by c1ass_state.
/snacks/state PUT Update blobs state info by _id. This call accepts a list of (id, c1ass, c1ass_state) objects, updates their associated blobs in the database.
/snacks/class/names GET Get the list of class names. This call returns a list of the class names that a blob can be classified by.
/snacks/last GET Get the last image. This call returns the latest image by date_created DESC. If none exist, null is returned.
/snacks/last/{int:n} GET Get the last n images. This call returns a list of the latest n images by date_created DESC.
/snacks/last/summary GET Get the latest summary. This call returns a summary of the latest processed images including the new, duplicate and removed blobs. If no images exist, it returns null.

Snapshot Naming Convention

When a camera snapshot is taken, The image will be written into a creation folder according to the snapshot’s date-time,


e.g. snack-2015_06_17-13_14_58 is created at date 2015-06-17 and time 13:14:58.

The result JSON for an image, for example, requests for the last image using curl command.

curl http://snack-web:8000/api/snacks/last

For a list of images, for example, requests for all snack images using curl command.

curl http://snack-web:8000/api/snacks/