Transdermal Optical Imaging (TOI™)

Transdermal Optical Imaging™ (TOI) is an imaging technology by NuraLogix that uses a digital camera and advanced image processing to extract facial blood-flow data from a human subject.

As a person's heart beats, the color of their skin undergoes minute variations. TOI™ captures and amplifies these variations and uses them to extract blood-flow information. When done from biologically significant regions of interest of the person's face, the result is called facial blood-flow information.

Transdermal Optical Imaging (TOI™)

There are three pre-requisites to extracting useful facial blood-flow information:

  1. A continuous sequence of images of a person's face (typically produced by a camera or a video file)

  2. Accurate image timestamps (typically produced by the camera or read from the video file) and

  3. Facial feature landmarks (typically produced by a face tracking library)


DeepAffex™ is NuraLogix's overarching solution for extracting and processing facial blood-flow information.

For desktop applications, you can extract facial blood-flow information using the DeepAffex™ Extraction Library which implements TOI™. Then you can send it to the DeepAffex™ Cloud to estimate several biological signals such as pulse rate, heart rate variability and more. NuraLogix™ has also developed several neural network models that can also predict biosignals like blood pressure or health markers like stress index.

The figure below shows the architecture of a DeepAffex™-based desktop application:

Architecture of a DeepAffex™ desktop application

In addition to the DeepAffex™ Extraction Library, you will need a method of producing a sequence of images (a camera or a video file,) a face-tracking engine and networking code that communicates with the DeepAffex™ Cloud, either using HTTP REST or WebSockets.

Mobile and Web

To develop iOS or Android apps, you should use the higher-level Anura Core SDK. On the web, you should use the Web Measurement Service.

The next chapter walks through a simple Python example that can extract facial blood-flow, send it to the DeepAffex™ Cloud for processing and display results.