descpatch_GRAD

PURPOSE

Patch descriptor based on histogrammed gradient [Lowe's SIFT descriptor].

SYNOPSIS

function desc = descpatch_GRAD( I, sigmas, ch2params )

DESCRIPTION

 Patch descriptor based on histogrammed gradient [Lowe's SIFT descriptor].

 Descriptor for an image that is fairly robust to small perturbations of the
 image. 

 INPUTS
   I               - MxN double image with most vals in range [-1,1]
   sigmas          - vector of sigmas, scales at which to look at gradient
   ch2params       - see imagedesc_ch2desc

 OUTPUTS
   desc            - 1xp feature vector

 See also IMAGEDESC, DESCPATCH_FB, IMAGEDESC_CH2DESC

CROSS-REFERENCE INFORMATION

This function calls:

imagedesc_ch2desc Helper, converts descriptor in array format to vector or histogram.

This function is called by:

imagedesc_generate Generate parameters for image or cuboid descriptor.