By “invert”, most people mean change black to white and visa versa, and this can be done by a simple line of code.

DicomObjects.NET

Set the DicomImage.Invert property:

DicomImage_1.Invert = true;

DicomObjects.COM

Set the DicomImage.Width property to some negative value:

DicomImage.Width = DicomImage.Width * -1

If however, you wish to rotate an image, then see the FlipState COM/.NET and [RotateState]COM/.NET properties of the image.