There are three types of Refresh in DicomObjects:
This routine fires automatically when any of the following display settings gets changed:
internal refresh ONLY refreshes the image area (the on-screen rectangle area occupied by the displayed image)
Call DicomImage.Refresh to force a redraw within the Image cell occupied by that Image. This routine does a little bit more than what internal refresh does as it not only refresh the image area but also areas not occupied by the image (if the image is smaller than it’s image cell)
Call DicomViewer.Refresh to force a redraw of the entire area of the DicomViewer. If the DicomViewer has multiple rows and columns (multiple image cells), this routine refreshes all images that are being displayed.
You do not need to call DicomViewer.Refresh most of the time as DicomObjects will handle it for you, unless you want to force a re-draw.