Hale Smith and George Walker are two of our most eminent black composers. And by conventional standards both are eminently successful.

Two words by Walker capped last night's concert of the New York Philharmonic's unprecedented week-long festival called "Celebration of Black Composers: Spanning Two Centuries of Music." And Smith's new work, "Innerflexions," will be performed at the end of tonight's final concert - in its world premiere.

The festival is designed to present in one week an overview of the best in black music from the mid-18th century to the present. To be chosen for such places of honor on the programs would seem to give assurance to Walker and Smith that they have really made it in every sense musically.

And their works are not being performed only at the festival. Walker's piano concerto, played by the Philarmonic last night, was premiered a year and a half ago by the National Symphony Orchestra, has already been performed by nine other orchestras, and has been recorded by Columbia as the ninth installment in its notable Black Composers Series. Smith's "Contours for Orchestra" also was recently done by the National Symphony, as well as numerous other organizations.

But all of this activity does not signal the liberation, at long last, of the black classical music composers from a two-century tradition of neglect and tokenism.

The key to the black composers's dilemma lies in that adjective "black." Walker does not read in the paper simply that he is one of America's finest composers, which he is. That word "black" is always there. And the same is true for Smith and their other colleagues at this festival, which is probably the largest survey of music by black composers ever put on by any orchestra, much less the Philharmonic.

For these creators and their creation, America is still a segregated country.

During an interview yesterday at Avery Fisher Hall, the Philharmonic's home, Smith was shown some words he wrote six years ago:

"Unless the work of Afro-American artists is allowed to succeed or fail by comparison - or in competition - with the works of the entire national and world cultures, we will have no valid standards of measurement by which they can be measured and judged on their own merits. And unless they are treated in this way, we will continue to have the patronizing 'Black Arts Presentations' which, in reality, solve no problems and still allow white America to suspend its critical faculties by deferring to the supposedly higher question of giving the black artist his day in the sun."

Smith, an amiable an unassuming man of 52, was asked if things hadn't improved, and he replied, "Not at all and I doubt if they ever will improve."

Then Walker, who is 54, made the same point this way: "Music by black composers just has failed to gain the full measure of respect that it deserves."

Statistics certainly support their opinions. Of the 12 compositions on the festival's orchestral program, eight are being played for the first time in New York. And few works by blacks have been played during the regular seasons of the Philharmonic, the world's second-oldest orchestra, concedes Leon Thompson, himself black and the Philharmonic's director of educational activities. Thompson, who will conduct tonight's concert, and Paul Freeman, who directed last night's program and is the Detroit Symphony's conductor-in-residence, put together the festival.

Walker, Smith and Thompson point to three reasons for the continuing undervaluation of the works of blacks: lack of patronage but patronizing reviews; and general neglect.

The very fact that all conductors and soloists on the series are black demonstrates the first phenomenon. As Smith points out, "Conductors traditionally have given premieres to works that were written by their friends and most white friends." Another sign of the sign of the overwhelmingly white orientation of the Philharmonic, as well as most other orchestras, came this week when its one black player, Sanford Allen, resigned to pursue a solo career.

The patronizing tone of reviews particularly galls Walker. A piano sonata of his performed in the festival was described by one reviewer as similar to Prokofiev. "There's always this idea of, well, look at how well he can copy other composers. An this is distressing because it amounts to an unconscious effort to deny the originality of the black composer. What matters most about a piece is what is different about it, not what is similar."

And Smith cited a decidedly unfriendly review his "Contours" received from a Cincinnati critic. The work, wrote the critic, is "unbelievably tasteless and inept and has about as much business on a serious program as a chimpazee has on the last act of "King Lear."

Both men granted that the general neglect of contemporary black composers extends somewhat to their white colleagues as well, but it is more damaging for blacks because none of them ever got their feet in the artistic door.

Audiences all over the country usually don't get excited about most new music. Walker told a story about the Washington premiere of his concerto, which was well received. "I was sitting in a box at the Kennedy Center before the concert and two ladies entered a box two places down. There was about five minutes of chitchat and then one asked the other. "Where is your husband?" The other replied, "Oh, he just can't stand this modern junk so he decided to stay outside during this concerto."

Like most white composers, both have to support themselves with supplementary jobs. Walker is head of the Rugers music department in Newark and teaches at Baltimore's Peabody Conservatory. Smith has an assortment of odd jobs, which he refers to as "paying my dues" - they include doing arrangements for Dizzie Gillespie, writing television commercial jingles and working on copyright in fringement.

One outstanding exception to white indifference occurred to Walker during a discussion of his haunting "Lyric for Strings," which was on last night's program. He remembered that the work's first performance in orchestral form came at the invitation of Washington's Richard Bales with the National Gallery Orchestra. "Yes, Richard is an exception and he is a fine man," Walker observed.