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b7c9f8a29a550dcb1b51f5a1c3bb28ab.ppt

  • Количество слайдов: 54

Target Detection Images in Target Detection Images in

Design of a classifier of the form Design of a classifier of the form

NN leads to a Complex Classifier NN leads to a Complex Classifier

SVM leads to a Complex Classifier SVM leads to a Complex Classifier

Fast (and accurate) classifier Fast (and accurate) classifier

Input Blocks Input Blocks

+1 -1 Hyperplane +1 -1 Hyperplane

Non-Faces Rejected non-faces Non-Faces Rejected non-faces

Rejected points Rejected points

Define a distance between a point and a PDF by Define a distance between a point and a PDF by

In the case of face detection in images we have We Should Maximize (GEP) In the case of face detection in images we have We Should Maximize (GEP)

Maximize the distance between all the pairs of [face, non-face] The same Expression Minimize Maximize the distance between all the pairs of [face, non-face] The same Expression Minimize the distance between all the pairs of [face, face]

If the two PDF’s are assumed Gaussians, their KL distance is given by And If the two PDF’s are assumed Gaussians, their KL distance is given by And we get a similar expression

The MRC algorithm idea is strongly dependent on these assumptions, and it leads to The MRC algorithm idea is strongly dependent on these assumptions, and it leads to Fast & Accurate Classifier.

All faces detected with no false alarms All faces detected with no false alarms

Assume that Minimize variances and Gaussians Maximize mean difference *FLD - Fisher Linear Discriminant Assume that Minimize variances and Gaussians Maximize mean difference *FLD - Fisher Linear Discriminant

Maximize Minimize Maximize Minimize

In the MRC we got the expression for the distance If P(X)=P(Y)=0. 5 we In the MRC we got the expression for the distance If P(X)=P(Y)=0. 5 we maximize The distance of the Y points to the X-distribution The distance of the X points to the Y-distribution

Instead of maximizing the sum Minimize the inverse of the two expressions (the inverse Instead of maximizing the sum Minimize the inverse of the two expressions (the inverse represent the proximity)

Compute Minimize f(θ) & find thresholds Remove Sub-set END Compute Minimize f(θ) & find thresholds Remove Sub-set END

No more Kernels Project onto the next Kernel Face Is value in Non Face No more Kernels Project onto the next Kernel Face Is value in Non Face

Input block Face/ Non. Face Input block Face/ Non. Face

Input block Face/ Non. Face Input block Face/ Non. Face

Searching targets in a given scale, for a 1000 by 1000 pixels image, the Searching targets in a given scale, for a 1000 by 1000 pixels image, the classifier is applied 1 e 6 times (even if no scale is involved!!)

While allowing outliers for better generalization behavior While allowing outliers for better generalization behavior