In celebration of Abraham Lincoln's birthday, the National Portrait Gallery will place on view today an 1864 portrait of Lincoln, a gift of Mr. and Mrs. David A. Morse of Washington. It was painted by William Willard (1819-1904), but credit for the likeness is not his alone.

Though President Lincoln sat for Willard on more than one occasion, the artist in this case based his painting on a photograph - the accurately named "Famouse, or Penny Profile," taken in Methew Brady's studio on Feb. 9, 1864.

The Portrait Gallery is concerned both with history and art, and its dual mission is acknowledged nicely by two other recently acquired paintings which also on display.

One, a rare life portrait of Lincoln's Civil War adversary, Gen. Robert E. Lee, was painted in 1864-65 by Edward Caledon Bruce (1825-1901), a Virginia painter (who was deafened by scarlet fever when he was 13.

The other, which Marvin Sadik, the gallery's director, calls "a splendidly sophisticated likeness and a truly marvelous work of art," is a self-portrait done in 1880 by the American Impressionist Mary Cassatt. Cassatt (1845-1926) painted only two self-portraits, this quickly sketched watercolor and a gouache of 1887, now in the collection of the Metropolitan Museum of Art.

Two other federal art museums, the National Gallery of Art and the Hirshhorn Museum and Sculpture Garden, also have been augmenting the collections.

The National Gallery yesterday announced that 12,000 photographs of important German works of art have been given to its library by the the German government. For a variety of reasons, not all of them esthetic, the Gallery's photo archive of some 670,000 prints contains more study images of Italian, French and British objects than of German works.

Art historian Horst W. Janson of the College Art Association encourged the German gift, and copies of the photographs - which survey German art from the days of Charlemagne through the 19th century - will be made available, at cost, to U.S. colleges and universities through the association.

The Central Institute for Art History in Munich chose the objects to be photographed. The pictures are in black and white. The Thyssen Foundation of Germany has contributed to the project, as has the German government, which provided 100,000 marks (about $40,000) towards the cost of making prints. The museum's photo achives will be a major component of the Center for Advanced Study in the Visual Arts, which will be housed in the Gallery's East Building.

(The first show, to be held in 1978, in the first East Building's special exhibition space, will be of objects lent by state museums in Dresden in East Germany. Though the Gallery has yet to announce the East German exhibition, a Gallery official yesterday denied that the delay was in any was connected with yesterday's acceptance of the West German gift.)

The Hirschhorn, which was built to house the vast collection of Joseph H. Hirshhorn, its founder, also has been adding to its holdings. Some 120 works of art, by some 90 artists, will be included in "Acquisitions: 1974-1977," which will open at the Hirshhorn March 25.

The show of art works acquired both through gift and purchase, will reflect decisions taken by museum officials since the date of Hirshhorn's gift.