image - What's mean a compact and discriminative descriptor ? -

image - What's mean a compact and discriminative descriptor ? -

i read in article

both sift , surf descriptors show discriminating properties. however, not compact.

what's meaning of discrimination , compactness here ?

let me give example.

assume, have phone. if tell you, company1, recognize phones made other companies. through, not recognize company1 phones. descriptor not discriminant enough.

if tell you, is company1 , model 5s, recognize much more phones. discriminant descriptor, not compact.

if compress company1 model 5s number (number in sorted list of phones of companies), allow 53 - descriptor both compact , discriminative.

image image-processing sift surf feature-extraction