Standard ACR-NEMA/DICOM fashion to store overlays :

In a bytes, 8 pixels are concerned (Overlay Bits Allocated = [1] )
Overlay Data length = 29282 (Overlay Rows * Overlay Columns)/8

D 6000|0010 lg :        x(2)        2 [US]               [Overlay Rows] [484]
D 6000|0011 lg :        x(2)        2 [US]            [Overlay Columns] [484]
D 6000|0015 lg :        x(2)        2 [IS][Number of Frames in Overlay] [1 ]
D 6000|0022 lg :       x(1e)       30 [LO]        [Overlay Description] [Siemens MedCom Object Graphics]
D 6000|0040 lg :        x(2)        2 [CS]               [Overlay Type] [G ]
D 6000|0050 lg :        x(4)        4 [SS]             [Overlay Origin] [1\1]
D 6000|0051 lg :        x(2)        2 [US]         [Image Frame Origin] [1]
D 6000|0100 lg :        x(2)        2 [US]     [Overlay Bits Allocated] [1]
D 6000|0102 lg :        x(2)        2 [US]       [Overlay Bit Position] [0]
D 6000|3000 lg :     x(7262)    29282 [OW]               [Overlay Data] [gdcm::NotLoaded]

Get the Data, expand them !
Hope there is never some oddities in Number of Frames in Overlay, 
   Overlay Origin,Overlay Bit Position, etc .