Official websites use .gov
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.gov website belongs to an official
government organization in the United States.
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A lock (
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connected to the .gov website. Share sensitive
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Gray spatial pyramid representation. The first row and third row: two images from different subjects and grids for levels L = 0 to L = 2; the second row and the fourth row: histogram representations corresponding to each level. The final PHG vector is a concatenation of vectors (histograms) for all levels.
