Overlays Overview

An "Overlay Plane" describes graphics or bit-mapped text that is associated with an image or has its own existence within a series. It may also describe a ROI in an Image.

Each "Overlay Plane" is one bit deep (1BPP). Sixteen separate planes may be associated with an image or exist as "Standalone Overlays" in a series.

Overlay pixel data is stored either in "Overlay Data" (60xx, 3000) or embedded in the "Image Pixel Data" (7FE0, 0010).

LEADTOOLS offers a number of methods and properties to manipulate overlays in DICOM Data Sets.

DicomDataSet.OverlayCount can be used to obtain the number of overlays in the DICOM Data Set. Call DicomDataSet.GetOverlayAttributes to retrieve the attributes of an overlay and DicomDataSet.GetOverlayImage to retrieve the "Overlay Data" (60xx,3000) for a single-frame overlay or DicomDataSet.GetOverlayImages for a multi-frame one.DicomDataSet.GetOverlayActivationLayer lets you get the activation layer for the overlay.

LEADTOOLS also allows you to insert a new or update an existing overlay. Call DicomDataSet.SetOverlayAttributesto set the attributes of a certain overlay and then call DicomDataSet.SetOverlayImage or DicomDataSet.SetOverlayImagesto set its data.

To delete all the elements related to an overlay call DicomDataSet.DeleteOverlay.