Image Processing Reference
In-Depth Information
Fig. 1.8. The patterns that excite the cells of V1 are shown on the
left
.Onthe
right
, a plausible
additive wiring of LGN cell responses to obtain a directional sensitivity of a simple cell is
shown
the spatial frequency information is important because, on one hand, it encodes the
sizes of objects, while on the other hand, it encodes the granularity or the scale of
repetitive patterns (textures).
1.8 Face Recognition in Humans
Patients suffering from
prosopagnosia
have a particular difficulty in recognizing face
identities. They can recognize the identities of familiar persons, if they have access to
other modalities, e.g., voice, walking pattern, length, or hairstyle. Without nonfacial
cues, the sufferers may not even recognize family members, or even their own faces
may be foreign to them. They often have good ability to recognize other objects that
are nonfaces. In many cases, they become prosopagnosic after a stroke or a surgical
intervention.
There is significant evidence, both from studies of prosopagnosia and from stud-
ies of brain damage, that face analysis engages special signal processing in visual
cortex that is different from processing of other objects [13, 68, 79]. There is a gen-
eral agreement that approximately at the age of 12, the performance of children in
face recognition reaches adult levels, that there is already an impressive face recog-
nition ability by the age of 5, and that measurable preferences for face stimuli exist
