Image Labeler

Label images for computer vision applications

expand all in page

Description

TheImage Labelerapp enables you to label ground truth data in a collection of images. Using the app, you can:

Define rectangular regions of interest (ROI) labels, line ROI labels, pixel ROI labels, polygon ROI labels, point ROI labels, projected cuboid ROI labels, and scene labels. Use these labels to interactively label your ground truth data.
Use built-in detection or tracking algorithms to label your ground truth data.
Write, import, and use your own custom automation algorithm to automatically label ground truth. SeeCreate Automation Algorithm for Labeling.
Evaluate the performance of your label automation algorithms using a visual summary. SeeView Summary of Ground Truth Labels.
Export the labeled ground truth as agroundTruthobject. You can use this object for system verification or for training an object detector or semantic segmentation network. SeeTraining Data for Object Detection and Semantic Segmentation.
To learn more about this app, seeGet Started with the Image Labeler.

TheImage Labelerapp supports all image file formats supported by theimreadfunction and additionally supports the Digital Imaging and Communication in Medicine (DICOM) format including the ability to load multiframe data such as an ultrasound video. To read additional file formats supported by theImage Labelerapp, you can create animageDatastoreand use theReadFcnproperty. To label 2-D or 3-D medical image data stored in the DICOM, Neuroimaging Informatics Technology Initiative (NIfTI), or nearly raw raster data (NRRD) file formats, use theMedical Image Labeler(Medical Imaging Toolbox).

When loading images, if an image has a dimension larger than 8000 pixels or is a multiresolution image, theImage Labelerapp offers you the option to convert the image into a blocked image. Ablocked imageconsists of a large image that has been divided into smaller blocks that can fit in memory. Once the Image Labeler converts the large image into a blocked, you can process it in the app as you would any other image. While using blocked images enables you to process images in the app that you might not otherwise be able to, there are some limitations. For more information, seeLabel Large Images in the Image Labeler.

Open the Image Labeler App

MATLAB^®Toolstrip: On theAppstab, underImage Processing and Computer Vision, click the app icon.
MATLAB command prompt: EnterimageLabeler.

Programmatic Use

expand all

`imageLabeler`

imageLabeler打开一个新会话的应用,使你拉bel ground truth data in images.

`imageLabeler(imageFolder)`

imageLabeler(imageFolder)opens the app and loads all the images from the folder namedimageFolder.

The images in the folder can be unordered and can vary in size. To label a video, or a set of ordered images that resemble a video, use theVideo Labelerapp instead.

`imageLabeler(imageDatastore)`

imageLabeler(imageDatastore)opens the app and reads all of the images from animageDatastoreobject. TheReadFcnproperty of theimageDatastoreobject specifies how to read the data.

For example, to open the app with a collection of stop sign images:

stopSignsFolder = fullfile(toolboxdir("vision"),"visiondata","stopSignImages"); imds = imageDatastore(stopSignsFolder) imageLabeler(imds)

`imageLabeler(sessionFile)`

imageLabeler(sessionFile)opens the app and loads a savedImage Labelersession,sessionFile. ThesessionFileinput contains the path and file name. The MAT-file thatsessionFilepoints to contains the saved session.

`imageLabeler(gTruth)`

imageLabeler(gTruth)opens the app and loads agroundTruthobject . The ground truth object data source must be an image collection or animageDatastore.

More About

expand all

ROI Labels, Sublabels, and Attributes

On the left side of the app, theROI Labelspane contains the region of interest (ROI) label definitions that you can mark on the frames. You can create label definitions directly from this pane. Alternatively, you can create label definitions programmatically by using alabelDefinitionCreatorobject and then import these label definitions into an app session.

Selecting ROI Label and Drawing Tool for Your Application

You can use labeled data to train or validate algorithms such as image classifiers, object detectors, and semantic and instance segmentation networks. Consider your application when choosing a labeling drawing tool to create ROI labels. The figure below shows labeling techniques for four different applications.

Application	Label Types	Example
Image Classification	N/A	Boat, Plane
Object Detection	Line Rectangle Projected Rectangle
Semantic Segmentation	Pixel label Polygon
Instance Segmentation	Polygon

ROI Labels

AnROI labelis a label that corresponds to a region of interest (ROI) in a signal frame. The table describes the supported label types.

ROI Label	Description	Scene
`Rectangle`	Draw rectangular ROI labels (bounding boxes) around objects.
`Projected cuboid`	Draw cuboidal ROI labels (3-D bounding boxes).
`Line`	Draw linear ROI labels to represent lines. To draw a line ROI, use two or more points.
`Pixel label`	Assign labels to pixels for semantic segmentation. You can label pixels manually using polygons, brushes, or flood fill. For more information about pixel labeling, seeLabel Pixels for Semantic Segmentation.
`Polygon`	Draw a pixel-filled polygon for instance segmentation. You can label distinct instances of the same class. For more information about instance segmentation, seeLabel Objects Using Polygons
`Point`	Draw point ROI labels for keypoint detection in objects.

ROI Sublabels

AnROI sublabelis an ROI label that belongs to a parent label. Use ROI sublabels to provide a greater level of detail about the ROIs in your labeled ground truth data. For example, avehiclelabel might containheadlight,licensePlate, andwheelsublabels。您可以创建sublabels为矩形,polygon, line, and projected cuboid labels. For more details about sublabels, seeUse Sublabels and Attributes to Label Ground Truth Data.

ROI Attributes

AnROI attributespecifies additional information about an ROI label or sublabel. For example, in an ocean scene, attributes might include the type or color of a boat. The table describes the supported attribute types.

Attribute Type	Sample Attribute Definition	Sample Default Values
`Numeric Value`
`String`
`Logical`
`List`

For more details on attributes, seeUse Sublabels and Attributes to Label Ground Truth Data.

Algorithms

expand all

You can use label automation algorithms to speed up labeling within the app. To create your own label automation algorithm to use within the app, seeCreate Automation Algorithm for Labeling. You can also use one of the built-in algorithms by following these steps:

Import the data you want to label, and create at least one label definition.
On the app toolstrip, clickSelect Algorithmand select one of the built-in automation algorithms.
ClickAutomate, and then follow the automation instructions in the right pane of the automation window.

ACF People Detector

Detect and label people using aggregate channel features (ACF). This algorithm is based on thepeopleDetectorACFfunction. To use this algorithm, you must define at least one rectangle ROI label. You do not need to draw any ROI labels.

To help improve the algorithm results, first clickSettings. You can change any of these settings.

The pretrained people detector model that the algorithm uses — The'inria-100x41'model was trained using the INRIA person data set. The'caltech-50x21'model was trained using the Caltech Pedestrian data set.
The overlap ratio threshold, from 0 to 1, for detecting people — When rectangle ROIs overlap by more than this threshold, the algorithm discards one of the ROIs.
The classification score threshold for detecting people — Increase the score to increase the prediction confidence of the algorithm. Rectangles with scores below this threshold are discarded.

ACF Vehicle Detector(requiresAutomated Driving Toolbox)

Detect and label vehicles using aggregate channel features (ACF). This algorithm is based on thevehicleDetectorACF(Automated Driving Toolbox)function. To use this algorithm, you must define at least one rectangle ROI label. You do not need to draw any ROI labels.

To help improve the algorithm results, first clickSettings. You can change any of these settings.

The pretrained vehicle detector model that the algorithm uses — The'full-view'model was trained using unoccluded images of the front, rear, left, and right sides of vehicles. The'front-rear-view'model was trained using images of only the front and rear sides of the vehicle.
The overlap ratio threshold, from 0 to 1, for detecting vehicles — When rectangle ROIs overlap by more than this threshold, the algorithm discards one of the ROIs.
The classification score threshold for detecting vehicles — Increase the score to increase the prediction confidence of the algorithm. Rectangles with scores below this threshold are discarded.

You can also configure the detector with a calibrated monocular camera by importing amonoCamera(Automated Driving Toolbox)object into the MATLAB workspace. Specify the length and width ranges of the vehicle in world units, such as meters.

Version History

Introduced in R2018a

Image Labeler

Description

Open the Image Labeler App

Programmatic Use

`imageLabeler`

`imageLabeler(imageFolder)`

`imageLabeler(imageDatastore)`

`imageLabeler(sessionFile)`

`imageLabeler(gTruth)`

More About

ROI Labels, Sublabels, and Attributes

Algorithms

ACF People Detector

ACF Vehicle Detector(requiresAutomated Driving Toolbox)

Version History

See Also

Apps

Functions

Objects

Topics