Hi,
The purpose of feature extraction technique in image processing is to represent the image in its compact and unique form of single values or matrix vector. Low level feature extraction involves the automatic extraction of features from an image without doing any processing method.
DWT is used for high level feature extraction to investigate the characteristic of narrow and broad band. You may apply further processing to the coefficient values to extract the image feature vectors (refer to literature for various methods) or retain coefficients itself as a feature vector.
Kindly have a look at the following link:
Thanks
