Create Custom Reader Function

First, specify a custom reader as a function handle. The custom reader must have this syntax.

outputImage = readerFcn(sourceName,currentTimestamp)

The custom reader function loads an image fromsourceName, which corresponds to the current timestamp specified bycurrentTimestamp. For example, suppose you want to load the image at the third timestamp for a timestampsdurationvector that runs from 1 to 5 seconds. To specifycurrentTimestamp, at the MATLAB^®command prompt, enter this code.

timestamps = seconds(1:5); currIdx = 3; currentTimestamp = timestamps(currIdx);

TheoutputImageoutput from the custom function must be a grayscale or RGB image in any format supported by theimshowfunction. ThecurrentTimestampoutput is a scalar value that corresponds to the current frame that the function is executing.

Import Data Source into Video Labeler App

To import a custom data source into theVideo Labelerapp, first create agroundTruthDataSource对象。这个对象存储数据的源文件nd timestamps. Specify the name of the data source, the custom reader function handle that reads the data, and the timestamps by using this syntax.

gtSource= groundTruthDataSource(sourceName,readerFcn,timestamps)

To load this object into the app, at the MATLAB command prompt, enter this code.

videoLabeler(gtSource)

Alternatively, on the toolstrip of theVideo Labelerapp, selectImport>Custom Reader. Then, in the Load Custom Data Source dialog box, specifyCustom reader functionas a function handle and also specifyData source name. In addition, you must import corresponding timestamps from the MATLAB workspace.

Import Data Source into Ground Truth Labeler App

To import the custom image data source into theGround Truth Labeler(Automated Driving Toolbox)app, on the app toolstrip, selectImport>Add Signals. Then, in the dialog box, setSource TypetoCustom Image. You can then specify the custom reader function, data source name, and timestamps, and then clickAdd Sourceto load the image data source.