8 research outputs found
Fine-graind Image Classification via Combining Vision and Language
Fine-grained image classification is a challenging task due to the large
intra-class variance and small inter-class variance, aiming at recognizing
hundreds of sub-categories belonging to the same basic-level category. Most
existing fine-grained image classification methods generally learn part
detection models to obtain the semantic parts for better classification
accuracy. Despite achieving promising results, these methods mainly have two
limitations: (1) not all the parts which obtained through the part detection
models are beneficial and indispensable for classification, and (2)
fine-grained image classification requires more detailed visual descriptions
which could not be provided by the part locations or attribute annotations. For
addressing the above two limitations, this paper proposes the two-stream model
combining vision and language (CVL) for learning latent semantic
representations. The vision stream learns deep representations from the
original visual information via deep convolutional neural network. The language
stream utilizes the natural language descriptions which could point out the
discriminative parts or characteristics for each image, and provides a flexible
and compact way of encoding the salient visual aspects for distinguishing
sub-categories. Since the two streams are complementary, combining the two
streams can further achieves better classification accuracy. Comparing with 12
state-of-the-art methods on the widely used CUB-200-2011 dataset for
fine-grained image classification, the experimental results demonstrate our CVL
approach achieves the best performance.Comment: 9 pages, to appear in CVPR 201
Towards Video Anomaly Retrieval from Video Anomaly Detection: New Benchmarks and Model
Video anomaly detection (VAD) has been paid increasing attention due to its
potential applications, its current dominant tasks focus on online detecting
anomalies% at the frame level, which can be roughly interpreted as the binary
or multiple event classification. However, such a setup that builds
relationships between complicated anomalous events and single labels, e.g.,
``vandalism'', is superficial, since single labels are deficient to
characterize anomalous events. In reality, users tend to search a specific
video rather than a series of approximate videos. Therefore, retrieving
anomalous events using detailed descriptions is practical and positive but few
researches focus on this. In this context, we propose a novel task called Video
Anomaly Retrieval (VAR), which aims to pragmatically retrieve relevant
anomalous videos by cross-modalities, e.g., language descriptions and
synchronous audios. Unlike the current video retrieval where videos are assumed
to be temporally well-trimmed with short duration, VAR is devised to retrieve
long untrimmed videos which may be partially relevant to the given query. To
achieve this, we present two large-scale VAR benchmarks, UCFCrime-AR and
XDViolence-AR, constructed on top of prevalent anomaly datasets. Meanwhile, we
design a model called Anomaly-Led Alignment Network (ALAN) for VAR. In ALAN, we
propose an anomaly-led sampling to focus on key segments in long untrimmed
videos. Then, we introduce an efficient pretext task to enhance semantic
associations between video-text fine-grained representations. Besides, we
leverage two complementary alignments to further match cross-modal contents.
Experimental results on two benchmarks reveal the challenges of VAR task and
also demonstrate the advantages of our tailored method.Comment: This work has been submitted to the IEEE for possible publication.
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