4,605 research outputs found
Learning Dynamic Feature Selection for Fast Sequential Prediction
We present paired learning and inference algorithms for significantly
reducing computation and increasing speed of the vector dot products in the
classifiers that are at the heart of many NLP components. This is accomplished
by partitioning the features into a sequence of templates which are ordered
such that high confidence can often be reached using only a small fraction of
all features. Parameter estimation is arranged to maximize accuracy and early
confidence in this sequence. Our approach is simpler and better suited to NLP
than other related cascade methods. We present experiments in left-to-right
part-of-speech tagging, named entity recognition, and transition-based
dependency parsing. On the typical benchmarking datasets we can preserve POS
tagging accuracy above 97% and parsing LAS above 88.5% both with over a
five-fold reduction in run-time, and NER F1 above 88 with more than 2x increase
in speed.Comment: Appears in The 53rd Annual Meeting of the Association for
Computational Linguistics, Beijing, China, July 201
Physical Representation-based Predicate Optimization for a Visual Analytics Database
Querying the content of images, video, and other non-textual data sources
requires expensive content extraction methods. Modern extraction techniques are
based on deep convolutional neural networks (CNNs) and can classify objects
within images with astounding accuracy. Unfortunately, these methods are slow:
processing a single image can take about 10 milliseconds on modern GPU-based
hardware. As massive video libraries become ubiquitous, running a content-based
query over millions of video frames is prohibitive.
One promising approach to reduce the runtime cost of queries of visual
content is to use a hierarchical model, such as a cascade, where simple cases
are handled by an inexpensive classifier. Prior work has sought to design
cascades that optimize the computational cost of inference by, for example,
using smaller CNNs. However, we observe that there are critical factors besides
the inference time that dramatically impact the overall query time. Notably, by
treating the physical representation of the input image as part of our query
optimization---that is, by including image transforms, such as resolution
scaling or color-depth reduction, within the cascade---we can optimize data
handling costs and enable drastically more efficient classifier cascades.
In this paper, we propose Tahoma, which generates and evaluates many
potential classifier cascades that jointly optimize the CNN architecture and
input data representation. Our experiments on a subset of ImageNet show that
Tahoma's input transformations speed up cascades by up to 35 times. We also
find up to a 98x speedup over the ResNet50 classifier with no loss in accuracy,
and a 280x speedup if some accuracy is sacrificed.Comment: Camera-ready version of the paper submitted to ICDE 2019, In
Proceedings of the 35th IEEE International Conference on Data Engineering
(ICDE 2019
Cascade R-CNN: Delving into High Quality Object Detection
In object detection, an intersection over union (IoU) threshold is required
to define positives and negatives. An object detector, trained with low IoU
threshold, e.g. 0.5, usually produces noisy detections. However, detection
performance tends to degrade with increasing the IoU thresholds. Two main
factors are responsible for this: 1) overfitting during training, due to
exponentially vanishing positive samples, and 2) inference-time mismatch
between the IoUs for which the detector is optimal and those of the input
hypotheses. A multi-stage object detection architecture, the Cascade R-CNN, is
proposed to address these problems. It consists of a sequence of detectors
trained with increasing IoU thresholds, to be sequentially more selective
against close false positives. The detectors are trained stage by stage,
leveraging the observation that the output of a detector is a good distribution
for training the next higher quality detector. The resampling of progressively
improved hypotheses guarantees that all detectors have a positive set of
examples of equivalent size, reducing the overfitting problem. The same cascade
procedure is applied at inference, enabling a closer match between the
hypotheses and the detector quality of each stage. A simple implementation of
the Cascade R-CNN is shown to surpass all single-model object detectors on the
challenging COCO dataset. Experiments also show that the Cascade R-CNN is
widely applicable across detector architectures, achieving consistent gains
independently of the baseline detector strength. The code will be made
available at https://github.com/zhaoweicai/cascade-rcnn
Fast Video Classification via Adaptive Cascading of Deep Models
Recent advances have enabled "oracle" classifiers that can classify across
many classes and input distributions with high accuracy without retraining.
However, these classifiers are relatively heavyweight, so that applying them to
classify video is costly. We show that day-to-day video exhibits highly skewed
class distributions over the short term, and that these distributions can be
classified by much simpler models. We formulate the problem of detecting the
short-term skews online and exploiting models based on it as a new sequential
decision making problem dubbed the Online Bandit Problem, and present a new
algorithm to solve it. When applied to recognizing faces in TV shows and
movies, we realize end-to-end classification speedups of 2.4-7.8x/2.6-11.2x (on
GPU/CPU) relative to a state-of-the-art convolutional neural network, at
competitive accuracy.Comment: Accepted at IEEE Conference on Computer Vision and Pattern
Recognition (CVPR), 201
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