Preprocessing Overview Preprocessing to enhance recognition performance in
- Slides: 25
Preprocessing Overview • Preprocessing to enhance recognition performance in the presence of: - Illumination variations - Pose/expression/scale variations - Resolution enhancement (deblurring) • Stand-alone recognition system • Preprocessing/recognition results - Face Recognition Grand Challenge (NIST)
Face Recognition Problem: Current state-of-the-art face recognition systems degrade significantly in performance due to variations in pose, illumination, and blurring. Solution: IMAGE CAPTURE PREPROCESSING RESTORATION/ ENHANCEMENT FACE RECOGNITION SYSTEM POSE CORRECTION due to mismatch in facial position, facial expression and scale ILLUMINATION CORRECTION due to mismatch in lighting conditions in both indoor and outdoor environments DEBLURRING due to mismatch in camera focus, camera lenses, camera resolution and motion blur
Highlights of the approach • No a priori information with regards to pose orientation, camera parameters, etc • No laser scanned images for 3 D reconstruction • No manual detection of feature points • Preprocessing & Stand-Alone Recognition
Principle • Find a function which maps a given test (probe) image into the correct train (gallery) image • Approach where M is the number of training images • Select that is maximally bijective
Recognition Principle • A function ’f ‘ is found which maps points in the test (probe) to equivalent points in the train (gallery) domain (X) f range(X) where X = Test image (domain) Y X Y = Train image (co-domain) = Bijective function mapping X Y Test Train One to One and Onto (bijection)
Inverse Estimation • A function ’g ‘ is found which maps points in the train (gallery) to equivalent points in the test (probe) domain (Y) g range(Y) where Y = Train image (domain) X = Test image (co-domain) X Y = Bijective function mapping Y X Test Train
Measure of Bijectivity X f Y Blue, Green, Cyan Red Partition X where n is the total number of distinct blocks in X
Measure of Bijectivity X g Y Blue, Green, Cyan Red Partition Y where p is the total number of distinct blocks in Y
Measure of Bijectivity The Bijectivity score is given by: = Forward (test train) = Backward (train test) = Adaptive Forward (test train) = Adaptive Backward (train test) = constants and
Mapping Properties Train Image No. 1
Preprocessing Example
Preprocessing Performance
Face recognition performance Metric used One-to-None Mapping Yale Subset-I Block Size-8 x 8; Search-56 x 56 Yale Subset-II Block Size-8 x 8; Search-88 x 88 Exhaustive Search 100 % 80 % Exhaustive Search with Constraints 100 % 83. 33 % Fast Search 98 % 83. 33 % Table 4. 2 Yale Results-Stand Alone Recognition-II
Face recognition performance PIE Subset- Exhaustive Search Block Size-8 x 8; Search-72 x 72 One-to-None Mapping One-to-One Mapping Stand Alone Recognition Performance 91. 18 % 95. 59 % Table 4. 4 PIE Database-Stand Alone Recognition PCA-based Approach recognition accuracy: 5. 88 %
Preprocessing for Illumination Correction Training Test Preprocessed
Preprocessing for Illumination Correction • Algorithm based on image adaptive least squares illumination correction Training image A Image A illuminated as B Testing image B Adaptive segmentation Image B illuminated as A Least squares estimate of illumination
Preprocessing Results Illumination Correction Enrollment : Process of accepting the image and creating a feature set for recognition. Set tested (Yale) Enrollment Rate (Commercial face recognition system) Original 56 % Preprocessed 90 %
Comparison with Existing Methods Test subset 3 D Morphable Model Our algorithm PIE frontal 99. 8 % 99. 6 % • 3 D morphable models : • Good results (FRVT 2002). • Very complex, computationally expensive, • manual labeling of features 1. T. Vetter and V. Blanz, “Face Recognition Based on Fitting a 3 D Morphable Model, ” IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 25, no. 9, pp. 1063 --1075, Sept. 2003.
Preprocessing Example train Vector Field Representation of f test Preprocessed Test Image
Preprocessing Example Notre Dame Database
Preprocessing Example Notre Dame Database
Recognition Example With the correct gallery Gallery Probe Bijective Mapping White Region measure of bijectivity (52. 91%)
Recognition Example With the incorrect gallery Gallery Probe Bijective Mapping White Region measure of bijectivity (33. 94%)
Face Recognition Performance Notre Dame Database
Conclusion and Future Work • New algorithm for registration and illumination correction to enhance the performance of face recognition systems • Algorithm is based on properties of the mapping between test and train data • Mapping produces similarity scores which can be used for a stand-alone face recognition algorithm • Extend algorithm for high resolution data • Reduce algorithm complexity
- Grammar to enrich and enhance writing
- Cosmetics are substances that are used to enhance
- A salad to stimulate appetite
- Fashion cycle
- Enhance an image
- Can hypnosis force people to act against their will
- Enhance an image
- Nanyang jc subject combination
- Cspnet
- Enhance life
- Neural network data preprocessing
- Document preprocessing
- Password hashing and preprocessing
- Image preprocessing
- Preprocessing fem
- Outlier
- Password hashing and preprocessing
- Sequential feature selection
- Major tasks in data preprocessing
- Data integration in data preprocessing
- Applytopup
- Aggregation in data preprocessing
- Image url to text
- Preprocessing in image processing
- Finite element example
- Data preprocessing