2,580 research outputs found
Backtracking Spatial Pyramid Pooling (SPP)-based Image Classifier for Weakly Supervised Top-down Salient Object Detection
Top-down saliency models produce a probability map that peaks at target
locations specified by a task/goal such as object detection. They are usually
trained in a fully supervised setting involving pixel-level annotations of
objects. We propose a weakly supervised top-down saliency framework using only
binary labels that indicate the presence/absence of an object in an image.
First, the probabilistic contribution of each image region to the confidence of
a CNN-based image classifier is computed through a backtracking strategy to
produce top-down saliency. From a set of saliency maps of an image produced by
fast bottom-up saliency approaches, we select the best saliency map suitable
for the top-down task. The selected bottom-up saliency map is combined with the
top-down saliency map. Features having high combined saliency are used to train
a linear SVM classifier to estimate feature saliency. This is integrated with
combined saliency and further refined through a multi-scale
superpixel-averaging of saliency map. We evaluate the performance of the
proposed weakly supervised topdown saliency and achieve comparable performance
with fully supervised approaches. Experiments are carried out on seven
challenging datasets and quantitative results are compared with 40 closely
related approaches across 4 different applications.Comment: 14 pages, 7 figure
Res2Net: A New Multi-scale Backbone Architecture
Representing features at multiple scales is of great importance for numerous
vision tasks. Recent advances in backbone convolutional neural networks (CNNs)
continually demonstrate stronger multi-scale representation ability, leading to
consistent performance gains on a wide range of applications. However, most
existing methods represent the multi-scale features in a layer-wise manner. In
this paper, we propose a novel building block for CNNs, namely Res2Net, by
constructing hierarchical residual-like connections within one single residual
block. The Res2Net represents multi-scale features at a granular level and
increases the range of receptive fields for each network layer. The proposed
Res2Net block can be plugged into the state-of-the-art backbone CNN models,
e.g., ResNet, ResNeXt, and DLA. We evaluate the Res2Net block on all these
models and demonstrate consistent performance gains over baseline models on
widely-used datasets, e.g., CIFAR-100 and ImageNet. Further ablation studies
and experimental results on representative computer vision tasks, i.e., object
detection, class activation mapping, and salient object detection, further
verify the superiority of the Res2Net over the state-of-the-art baseline
methods. The source code and trained models are available on
https://mmcheng.net/res2net/.Comment: 11 pages, 7 figure
DC-SPP-YOLO: Dense Connection and Spatial Pyramid Pooling Based YOLO for Object Detection
Although YOLOv2 approach is extremely fast on object detection; its backbone
network has the low ability on feature extraction and fails to make full use of
multi-scale local region features, which restricts the improvement of object
detection accuracy. Therefore, this paper proposed a DC-SPP-YOLO (Dense
Connection and Spatial Pyramid Pooling Based YOLO) approach for ameliorating
the object detection accuracy of YOLOv2. Specifically, the dense connection of
convolution layers is employed in the backbone network of YOLOv2 to strengthen
the feature extraction and alleviate the vanishing-gradient problem. Moreover,
an improved spatial pyramid pooling is introduced to pool and concatenate the
multi-scale local region features, so that the network can learn the object
features more comprehensively. The DC-SPP-YOLO model is established and trained
based on a new loss function composed of mean square error and cross entropy,
and the object detection is realized. Experiments demonstrate that the mAP
(mean Average Precision) of DC-SPP-YOLO proposed on PASCAL VOC datasets and
UA-DETRAC datasets is higher than that of YOLOv2; the object detection accuracy
of DC-SPP-YOLO is superior to YOLOv2 by strengthening feature extraction and
using the multi-scale local region features.Comment: 23 pages, 9 figures, 9 table
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