EXHIBIT 5.1



                                SULLIVAN & WORCESTER LLP
                                ONE POST OFFICE SQUARE
                              BOSTON, MASSACHUSETTS 02109
                                    (617) 338-2800
                                 FAX NO. 617-338-2880
    IN WASHINGTON, D.C.                                    IN NEW YORK CITY
1025 CONNECTICUT AVENUE, N.W.                              767 THIRD AVENUE
   WASHINGTON, D.C. 20036                              NEW YORK, NEW YORK 10017
      (202) 775-8190                                         (212) 486-8200
   FAX NO. 202-293-2275                                    FAX NO. 212-758-2151






                                                              December 23, 1997





FOCUS Enhancements, Inc.
142 North Road
Sudbury, Massachusetts 01776

Gentlemen:

         We are familiar with the  Registration  Statement on Form S-3 (the "S-3
Registration  Statement")  to which this  opinion is an exhibit,  to be filed by
FOCUS  Enhancements,  Inc., a Delaware  corporation  (the  "Company"),  with the
Securities and Exchange Commission under the Securities Act of 1933, as amended.
The S-3  Registration  Statement  relates to the  proposed  public  offering  by
certain  securityholders  of the  Company of a total of  2,162,869  shares  (the
"Shares")  of the  Company's  Common  Stock,  $.01 par value per share  ("Common
Stock"),  consisting of (i) 732,869 Shares issued to  stockholders of TView Inc.
which was acquired by the Company  effective  September 30, 1996; (ii) 1,000,000
Shares  issued to Smith  Barney  Fundamental  Value Fund,  Inc.  (the "Fund") in
connection  with a  private  placement  in  September  1997 (the  "September  97
Offering");  (iii)  330,000  Shares  issuable to the Fund upon the exercise of a
warrant  (the  "Investor  Warrant")  that may be issued  to the  Fund;  and (iv)
100,000  Shares  issuable upon the exercise of warrants (the "Broker  Warrants")
issued to the  placement  agent in  connection  with the  September 97 Offering.
Hereinafter the Investor Warrant and the Broker Warrants shall be referred to as
the "Warrants".

         We have  acted  as  counsel  to the  Company  in  connection  with  the
preparation of the S-3 Registration  Statement,  and we have examined and relied
on  the  originals  or  copies,   certified  or  otherwise   identified  to  our
satisfaction  of all such  corporate  records  of the  Company  and  such  other
instruments   and  other   certificates  of  public   officials,   officers  and
representatives  of the  Company and such other  persons,  and we have made such
investigations of law, as we have deemed  appropriate as a basis for the opinion
expressed below. In making such examination, we





FOCUS Enahncements, Inc.
May 12, 1997
Page 2

have assumed the  genuineness of all  signatures,  the legal capacity of natural
persons,  the authenticity of all documents submitted to us as originals and the
conformity to the originals of all  documents  submitted to us as copies,  which
facts we have not  independently  verified.  As to various facts material to the
opinions set forth herein, we have relied without independent  verification upon
certificates  of public  officials and upon facts certified to us by officers of
the Company.  We express no opinion herein as to any laws other than the General
Corporation Law of the State of Delaware.

         Based upon the  foregoing,  we are of the opinion  that the Company has
corporate  power adequate for the issuance of the Shares  issuable in the manner
set forth in the S-3  Registration  Statement  and  offered  pursuant to the S-3
Registration  Statement.  The Shares issuable upon the exercise of the Warrants,
assuming  conversion or exercise on the date hereof (the "Relevant Shares") have
been duly  authorized  and  reserved  for  issuance.  Upon the  exercise  of the
Warrants into Shares and delivery of such Shares in accordance with the terms of
the Warrants,  the Relevant Shares so issued will be validly issued,  fully paid
and non-assessable.

         We hereby  consent to the  filing of this  opinion as an exhibit to the
S-3 Registration Statement.

                                                 Very truly yours,


                                                 /s/ SULLIVAN & WORCESTER LLP

                                                 SULLIVAN & WORCESTER LLP