What is Custom Vision?
Azure Custom Vision is an image recognition service that lets you build, deploy, and improve your own image identifiers. An image identifier applies labels (which represent classes or objects) to images, according to their visual characteristics. Unlike the Computer Vision service, Custom Vision allows you to specify the labels and train custom models to detect them.
What it does
The Custom Vision service uses a machine learning algorithm to analyze images. You, the developer, submit groups of images that feature and lack the characteristics in question. You label the images yourself at the time of submission. Then, the algorithm trains to this data and calculates its own accuracy by testing itself on those same images. Once you've trained the algorithm, you can test, retrain, and eventually use it in your image recognition app to classify new images. You can also export the model itself for offline use.
Classification and object detection
Custom Vision functionality can be divided into two features. Image classification applies one or more labels to an image. Object detection is similar, but it also returns the coordinates in the image where the applied label(s) can be found.
The Custom Vision service is optimized to quickly recognize major differences between images, so you can start prototyping your model with a small amount of data. 50 images per label are generally a good start. However, the service is not optimal for detecting subtle differences in images (for example, detecting minor cracks or dents in quality assurance scenarios).
Additionally, you can choose from several varieties of the Custom Vision algorithm that are optimized for images with certain subject material—for example, landmarks or retail items. For more information, see the Build a classifier or Build an object detector guides.
What it includes
The Custom Vision Service is available as a set of native SDKs as well as through a web-based interface on the Custom Vision website. You can create, test, and train a model through either interface or use both together.
Data privacy and security
As with all of the Cognitive Services, developers using the Custom Vision service should be aware of Microsoft's policies on customer data. See the Cognitive Services page on the Microsoft Trust Center to learn more.