How to Implement Image Capture Processing
Note: Before you begin, see Build your application with the library for Android.
To implement the image capture process, follow these steps:
- Begin with the Callback interface implementation. Its methods will be used to pass the data to and from the recognition service. Here are the brief recommendations on what the methods should do:
- The onRequestLatestFrame method should retrieve the image from the camera and pass it on to the IImageCaptureService.submitRequestedFrame method.
- The onFrameProcessed method is where you work with the results, display them to the user, etc.
- The onError method is for handling processing errors.
- Call the Engine.load method on the UI thread to create an engine object via which all other objects may be created. This object should be reused for every new operation and should not be created again in the same activity.
- Use the createImageCaptureService method of the Engine object to create a background recognition service (implementing the IImageCaptureService interface) on the UI thread. Only one instance of the service per application is necessary: multiple threads will be started internally.
- When the camera is ready, call the start method of the IImageCaptureService interface. Its required input parameters are the size and orientation of the video frame. You can also specify the rectangular area where the document is supposed to be (e.g. if your application displays a highlighted rectangle in the center of the image, this rectangle should be specified as the "area of interest").
The service will then start up several working threads and continue interacting with your application via the Callback interface. - Whenever the Callback.onRequestLatestFrame method is called, provide the current video frame from the camera by calling IImageCaptureService.submitRequestedFrame.
- The Callback.onFrameProcessed method will be called on the UI thread to return the result as an instance of the IImageCaptureService.Result class when the frame is processed.
- Process the applicable result using the IImagingCoreAPI functionality:
- load the captured image to an IImagingCoreAPI.Image interface instance;
- crop it with the IImagingCoreAPI.CropOperation in case perspective distortion should be corrected.
- Export the processed result to the server in one of available formats: JPG, PNG, PDF or WebP. It is recommended to use the Normal compression mode to keep high quality while minimizing the image size.
- When the appropriate result was get, as well as on pausing or quitting the application, call the IImageCaptureService.stop method to terminate the processing threads.
See the description of classes and methods in the API Reference section.
02.03.2022 12:59:15