In this paper, two improved intra angular prediction methods are proposed to enhance coding performance. The first method applies new four-tap interpolation filter algorithm. The reference samples at fractional position are interpolated by DCT-based or Gaussian interpolation filter. The second method proposes extended boundary prediction filter to reduce the prediction error. The experimental results show that for AI configuration, the overall coding gain is about 0.85% on average comparing to HEVC reference software while maintaining almost the same coding time.