Keyphrases
- basis vectors
- linear combination
- sparse coding
- feature space
- sparse representation
- basis functions
- nonnegative matrix factorization
- low dimensional
- training samples
- original data
- data sets
- natural images
- image processing
- data matrix
- image classification
- supervised learning
- image representation
- dimensionality reduction
- principal component analysis
- negative matrix factorization
- least squares
- small number