Hello im struggling with an implementation of this article: https://www.comp.nus.edu.sg/~tancl/publications/c2014/Using%20Pyramid%20of%20Histogram%20of%20Oriented%20Gradients%20on%20Natural%20Scene%20Text%20Recognition-final.pdf I performed bilinear interpolation over the histogram bins and the results are better with this interpolation, however on page 2 its also mentioned that a trilinear interpolation is added when the pyramid level reaches level 2. I have read this answer HOG Trilinear Interpolation of Histogram Bins and I completely understand the formula behind trilinear interpolation over 2x2 block sizes, but in this article we have a 3x3 block size and 7x7 on pyramid level 3, because these block sizes yield the best results. The main point about trilinear interpolation is that each pixel in a cell contributes to its local cell by a weight which is defined as the position in each block. I don't know how to represent the location of a pixel in 3x3 block size or what kind of formula should i use. Thank you for all your help! EDIT: Another explanation with 2x2 block size http://pep.ijieee.org.in/journal_pdf/11-126-142960909718-22.pdf Continue reading...
