FUNCTION hsi_detseg2a2d, DET_INDEX_MASK=det_index_mask, SEG_INDEX_MASK=seg_index_mask

a2d_index_mask = Bytarr( 27 )
IF Keyword_Set( DET_INDEX_MASK ) THEN BEGIN 
    n_el = 9
    mask_part = det_index_mask[0:8]
ENDIF ELSE IF Keyword_Set( SEG_INDEX_MASK ) THEN BEGIN
    n_el = 18
    mask_part = seg_index_mask[0:17]
ENDIF ELSE RETURN, Bytarr(27 )
mask_full = BytArr( n_el )
mask_full[0] = mask_part
list = Where( mask_full, count )
IF count GT 0 THEN BEGIN
    IF n_el EQ 9 THEN BEGIN 
        list = [ list, list+9, list + 18]
    ENDIF ELSE BEGIN 
        list2 = Where( list GE 9, count2 )
        IF count2 GT 0 THEN BEGIN 
            list = [list, list[list2] + 9 ]
        ENDIF 
    ENDELSE 
    a2d_index_mask[list] =  1
ENDIF

; just to be sure transfor it in bytes
RETURN, Byte( a2d_index_mask ) > 0B < 1B

END


;---------------------------------------------------------------------------
; End of 'hsi_detseg2a2d.pro'.
;---------------------------------------------------------------------------