title: Maximum intensity projection using bidirectional compositing with block skipping.
abstract: BACKGROUND
  Maximum intensity projection (MIP) is a volume rendering technique that determines the pixel intensity as the maximum of all values sampled along the viewing direction. MIP has been successfully applied to diagnose bone fractures in computed tomography (CT) and the stenosis of vascular structures in magnetic resonance angiography (MRA). However, MIP has a major drawback in that the depth and occlusion information cannot be perceived in the output images. The most universal way to alleviate this problem is to occasionally change the viewpoint for depth perception. To support this function in real time, MIP should be performed at an interactive frame rate.
  
  
  OBJECTIVE
  We develop an efficient rendering algorithm for MIP so that MIP is performed at an interactive frame rate without a loss of image quality.
  
  
  METHODS
  The proposed method predicts the position of the maximum intensity for each ray using blockwise maximum bounds, after which it performs bidirectional compositing toward both ends of the ray from this predicted position. During the compositing process, block skipping is used as an acceleration method.
  
  
  RESULTS
  The proposed method outperformed the block skipping method using the sequential compositing with a speed-up factor of 2.2 ∼ 2.8 depending on the data set without any degradation of the image quality.
  
  
  CONCLUSIONS
  We proposed an efficient rendering technique for MIP. Our method was superior to the conventional block skipping method with respect to the rendering speed and degree of performance consistency.
authors.affiliation: Department of Computer Science and Engineering, Seoul National University, Seoul, Korea.
authors.forename: Ohjae
authors.initials: O
authors.lastname: Kwon
authors.affiliation: Department of Computer Science and Engineering, Seoul National University, Seoul, Korea.
authors.forename: Sung-Tae
authors.initials: ST
authors.lastname: Kang
authors.affiliation: Department of Computer Software Engineering, Sangmyung University, Seoul, Korea.
authors.forename: Soo-Hong
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Computer Science, Sangmyung University, Seoul, Korea.
authors.forename: Yoon-Ho
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Computer Science and Engineering, Seoul National University, Seoul, Korea.
authors.forename: Yeong-Gil
authors.initials: YG
authors.lastname: Shin
mesh_terms: D000465:Algorithms; D044962:Data Compression / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: Maximum intensity projection; acceleration techniques; bidirectional compositing; block skipping; prediction of the starting position