Optimum Number of Blocks on each frame dissected to perform video retrieval ---Pitching scene retrieval for baseball games in terms of human sensation ---

The precision rate was much lower than the recall rate, when high recall rate was desired, in video retrieval because of unwanted video scenes contained in the designated scenes set. This paper describes an experimental study on the test of how to obtain high precision rate keeping the recall rate high, visually confirming the optimum number of dissected blocks used to perform the video retrieval in each video frame of baseball games. The test was carried out to check if the subjects could recognize the desired scenes correctly when sets of contiguous video frames, each dissected into one of 2 by 2 through 20 by 20 blocks, were demonstrated to the respective subjects in a random order of frame dissection into blocks. The result of the test showed that a satisfactory score was obtained from the frame consisting of 10 by 10 blocks. The result implies that unwanted scenes will be rejected from the pitching scenes sets when 10 by 10 blocks will be chosen for the video retrieval.