11. The method of claim 9 , further comprising: extracting an additional invisible junction feature descriptor; and adding a second feature point to the quantization tree for the additional invisible junction feature descriptor.
11. The method of claim 9 , further comprising: extracting an additional invisible junction feature descriptor; and adding a second feature point to the quantization tree for the additional invisible junction feature descriptor. 13. The method of claim 11 , wherein the feature point is added to the quantization tree by adding a leaf node including a page ID and coordinates (x, y) of the feature point.