After officially signing his 10-day contract with the Knicks and practicing for the first time with the team yesterday, Kenyon Martin declared he plans to change the negative perceptions about him. The Knicks could use a change in public opinion right about now, too.

The Knicks are in free fall going into tonight’s home game against the 76ers, having dropped four straight and going 14-15 since their 18-5 start. They have not won at the Garden since Feb. 4.

The 35-year-old Martin agreed to terms Thursday after being out of the NBA this season. The 6-foot-9, 230-pound forward affords the Knicks frontcourt depth with Rasheed Wallace and Marcus Camby still hurting.