"We also investigated hierarchical features where the image is overlaid with a grid of cell size c × c and pixels withins each cell are added up. This is same as downsampling the image and using the raw pixels in the downsampled image as features." (p. 3)
Comments
"We also investigated hierarchical features where the image is overlaid with a grid of cell size c × c and pixels withins each cell are added up. This is same as downsampling the image and using the raw pixels in the downsampled image as features." (p. 3)
http://www.eecs.berkeley.edu/Pubs/TechRpts/2009/EECS-2009-15...
Sounds similar to one level of a pyramid:
https://en.wikipedia.org/wiki/Pyramid_(image_processing)