Citation
Safa, Soodabeh
(2016)
Plant identification using combination of fuzzy c-means spatial pyramid matching, gist, multi-texton histogram and multiview dictionary learning.
Doctoral thesis, Universiti Putra Malaysia.
Abstract
Plants identification has become a significant and incentive research area. It is
estimated that about half of the world's plant species are still not identified. Making a
detailed knowledge of the identity and geographical distribution of plants is required
for an effective agricultural biodiversity. Most of the existing plant identification
methods are based on both the global shape features and the intact plant leaves.
However, for the non-intact leaves such as the deformed, partial and overlapped
leaves that largely exist in practice, the global shape features are not efficient and
these methods are not applicable.The dried leave parts and noise can degrade
identification results and affect the quality of the extracted features which lead to
poor classification results. Furthermore, feature extraction methods based on global
features such as shape, color and texture do not lead to accurate identification since
they cannot adapt to changing environment. In the real world, leaf images can be
simply affected by light, position, and size. To overcome this problem, in recent
years, researchers obtained some achievements with combination of invariant local
features such as Scale Invariant Feature Transform (SIFT) with global feature of leaf
images. Beside that, classic bag of visual words algorithm (BoVW) is based on kmeans
clustering and every SIFT feature belongs to one cluster and it leads to
decreasing classification results. Moreover with simple concatenating features,
classification results are not optimal. It is crucial to integrate these heterogeneous
features to create more accurate and robust classification results than using each
individual type of features.
This study first starts with some preprocessing phases for images with dried and
damaged parts in leaves, that applies on images while finding leaf as region of
interest (ROI) with Otsu's method. For next, instead of k-means clustring, Fuzzy cmeans
clustering is combined with Spatial Pyramid Matching image representation
to improve the accuracy of classification results. The Fuzzy c-means clustering
improved the accuracy of classification task to 40.53%. In the next phase, the local
SIFT descriptor is augmented with two global descriptors. One descriptor contains texture and color called Multi-Textron Histogram (MTH) and improved
classification results by second level of discrimination for leaves with similar color
and shape. Second one is gist from global features of leaf images. gist descriptor is
based on spatial layout of colors, orientation and principal texture. The combination
of gist, MTH and SIFT features increased the performance of image identification
and showed 49% accuracy. Moreover, instead of concatenating feature vectors
together and send to classifier, sparse coding and dictionary learning methods are
used and instead of considering all features as one view (visual feature), K-SVD
algorithm that is one of the famous algorithms for sparse representation is optimized
and developed to multi-view model.The experimental results prove that the proposed
methods has improved accuracy by 53.77% compared to concatenating features and
classic K-SVD dictionary learning model as well.
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