视觉显著性指导的红外与可见光图像融合算法

为了获取适合人眼观测的高质量红外与可见光融合图像,提出了一种基于视觉显著性指导的红外与可见光图像融合算法。首先,利用改进的流形排序法分别检测红外与可见光图像的视觉显著性区域;然后,采用非下采样轮廓波变换对红外和可见光图像进行多尺度、多方向分解,从而获取各自低频子带和高频子带,并将视觉显著性的检测结果用于指导分配低频子带的融合权重,即依据显著度大小赋予不同的权值,而高频子带的融合则依据局部标准差准则赋值;最后,通过非下采样轮廓波逆变换获得融合图像。实验结果表明:这种算法不仅可以保全可见光图像中的细节信息,而且能够精确地突显出红外目标信息,具有较好的视觉效果, 增强了红外与可见光复合前视系统的识别性能。     

WavNet — Visual saliency detection using Discrete Wavelet Convolutional Neural Network

In the recent advancements in image and video analysis, the detection of salient regions in the image becomes the initial step. This plays a crucial role in deciding the performance of such algorithms. In this work, a Multi-Resolution Feature Extraction (MRFE) technique that makes use of Discrete Wavelet Convolutional Neural Network (DWCNN) for generating features is employed. An Enhanced Feature Extraction (EFE) module extracts additional features from the high level features of the DWCNN, which are used to frame both channel as well as spatial attention models for yielding contextual attention maps. A new hybrid loss function is also proposed, which is a combination of Balanced Cross Entropy (BCE) loss and Edge based Structural Similarity (ESSIM) loss that effectively identifies and segments the salient regions with clear boundaries. The method is tested exhaustively with five different benchmark datasets and is proved superior to the existing state-of-the-art methods with a minimum Mean Absolute error (MAE) of 0.03 and F-measure of 0.956.     

A depth perception and visual comfort guided computational model for stereoscopic 3D visual saliency

With the emerging development of three-dimensional (3D) related technologies, 3D visual saliency modeling is becoming particularly important and challenging. This paper presents a new depth perception and visual comfort guided saliency computational model for stereoscopic 3D images. The prominent advantage of the proposed model is that we incorporate the influence of depth perception and visual comfort on 3D visual saliency computation. The proposed saliency model is composed of three components: 2D image saliency, depth saliency and visual comfort based saliency. In the model, color saliency, texture saliency and spatial compactness are computed respectively and fused to derive 2D image saliency. Global disparity contrast is considered to compute depth saliency. Particularly, we train a visual comfort prediction function to distinguish stereoscopic image pair as high comfortable stereo viewing (HCSV) or low comfortable stereo viewing (LCSV), and devise different computational rules to generate a visual comfort based saliency map. The final 3D saliency map is obtained by using a linear combination and enhanced by a “saliency-center bias” model. Experimental results show that the proposed 3D saliency model outperforms the state-of-the-art models on predicting human eye fixations and visual comfort assessment.     

Unsupervised Domain Adaptation Learning Algorithm for RGB-D Stairway Recognition

Detection and recognition of a stairway as upstairs, downstairs and negative (e.g., ladder, level ground) are the fundamentals of assisting the visually impaired to travel independently in unfamiliar environments. Previous studies have focused on using massive amounts of RGB-D scene data to train traditional machine learning (ML)-based models to detect and recognize stationary stairway and escalator stairway separately. Nevertheless, none of them consider jointly training these two similar but different datasets to achieve better performance. This paper applies an adversarial learning algorithm on the indicated unsupervised domain adaptation scenario to transfer knowledge learned from the labeled RGB-D escalator stairway dataset to the unlabeled RGB-D stationary dataset. By utilizing the developed method, a feedforward convolutional neural network (CNN)-based feature extractor with five convolution layers can achieve 100% classification accuracy on testing the labeled escalator stairway data distributions and 80.6% classification accuracy on testing the unlabeled stationary data distributions. The success of the developed approach is demonstrated for classifying stairway on these two domains with a limited amount of data. To further demonstrate the effectiveness of the proposed method, the same CNN model is evaluated without domain adaptation and the results are compared with those of the presented architecture.     

基于S曲线全局动态调光的改进算法

S曲线全局动态调光算法可以降低LED液晶显示器的功耗,同时能够提高显示图像的静态对比度,但该算法会造成部分图像色彩失真和细节丢失。针对这一问题,本文提出一种图像细节层分离与视觉显著性理论相结合的S曲线改进算法。首先,将原始图像转换至HSV色彩空间进行亮度和色度分离;然后,在图像亮度分量上采用双边滤波得到图像的基础层与细节层,基础层采用S曲线进行动态范围拉伸,实现像素补偿,细节层则运用视觉显著性理论进行分区与权值增强,弥补由像素补偿带来的细节损失;最后,将处理后的各层图像转换至RGB空间显示。将本文算法的仿真结果与原S曲线算法的结果进行对比。结果显示,本文算法在维持原算法功耗降低和静态对比度提升水平不变的基础上,解决了原算法在部分图像中出现的色彩失真和细节丢失问题,提升了图像的视觉显示效果,同时本文算法的仿真结果具有更大的信息熵和平均梯度。     

Geometry-Aware ICP for Scene Reconstruction from RGB-D Camera

The Iterative Closest Point (ICP) scheme has been widely used for the registration of surfaces and point clouds. However, when working on depth image sequences where there are large geometric planes with small (or even without) details, existing ICP algorithms are prone to tangential drifting and erroneous rotational estimations due to input device errors. In this paper, we propose a novel ICP algorithm that aims to overcome such drawbacks, and provides significantly stabler registration estimation for simultaneous localization and mapping (SLAM) tasks on RGB-D camera inputs. In our approach, the tangential drifting and the rotational estimation error are reduced by: 1) updating the conventional Euclidean distance term with the local geometry information, and 2) introducing a new camera stabilization term that prevents improper camera movement in the calculation. Our approach is simple, fast, effective, and is readily integratable with previous ICP algorithms. We test our new method with the TUM RGB-D SLAM dataset on state-of-the-art real-time 3D dense reconstruction platforms, i.e., ElasticFusion and Kintinuous. Experiments show that our new strategy outperforms all previous ones on various RGB-D data sequences under different combinations of registration systems and solutions.

     

视觉注意力检测综述

人类能够迅速地选取视野中的关键部分,选择性地将视觉处理资源分配给这些视觉显著的区域.在计算机视觉领域,理解和模拟人类视觉系统的这种注意力机制,得到了学界的大力关注,并显示出了广阔的应用前景.近年来,随着计算能力的增强以及大规模显著性检测数据集的建立,深度学习技术逐渐成为视觉注意力机制计算和建模的主要手段.综述了视觉注意力检测的最新研究进展,包括人眼关注点检测和显著物体检测,并讨论了当前流行的视觉显著性检测数据集和常用的评估指标.对基于深度学习的工作进行了综述,也对之前代表性的非深度学习模型进行了讨论,同时,对这些模型在不同的数据集上的性能进行了详细评估.最后探讨了该领域的研究趋势和未来的发展方向.     

基于ORB-SLAM2的实时网格地图构建

针对目前视觉SLAM（同时定位与地图构建）系统只能输出相机的运动轨迹图而不能生成用于路径规划和导航地图的缺点,提出了一种基于ORB-SLAM2的网格地图实时构建算法。首先,建立了一个适用于视觉SLAM的逆传感器模型（inverse sensor model,ISM）;针对ISM模型重新编排了网格地图算法的构建机制,并对其进行详细推导;最后,介绍了ORB-SLAM2网格地图构建的具体实施方案。通过实验,对ISM模型和网格地图模型进行分析,确保了算法的可行性;用单目相机和RGB-D深度相机进行实时实验,实现了网格地图的实时构建,且能够清晰地显现出障碍物位置,验证了所提算法的有效性。     

基于改进YOLO网络的双通道显著性目标识别算法

由于缺乏目标的先验信息,实时预警检测系统存在虚警率高、实时性偏低等问题,限制了实战环境下的广泛应用。为了提升目标检测识别的性能,本文提出了一种基于改进YOLO网络的双通道显著性目标识别算法,该算法利用红外图像与可见光互补特性进行多尺度融合,并在融合图像上采用显著性检测获取疑似目标区域,最后利用改进的识别网络对疑似区域进行多层次目标识别。改进的YOLO识别网络增加了一路辅助网络,改善整个特征提取网络的性能,并采用注意机制对辅助网络和骨干网络的特征信息融合,增强有效信息通道,抑制无效信息通道,提高网络识别效率。仿真实验结果表明,本文提出的模型可以有效地提高目标检测与识别精度,其实时性得到了大大增强。     

基于显著区域提取的红外图像舰船目标检测

针对复杂海面背景下红外图像舰船目标由于灰度不均匀、海杂波干扰大等因素造成的自动检测虚警率高、准确率低的问题,提出了一种显著区域提取和目标精确分割相结合的红外舰船目标检测方法。首先,利用基于图论的视觉显著性(Graph-based Visual Saliency ,GBVS)模型计算待检测图像的显著图,使得目标区域信息增强;其次,结合舰船目标先验信息（长短轴、面积等）,利用多级阈值划分算法提取关注的显著区域,并确定原图中候选目标区域;最后,利用空间约束模糊C均值(Fuzzy C-Means,FCM)算法对候选区域进行分割,结合目标先验知识对分割区域筛选并输出目标位置。所提方法在公开数据集IRShips上与相关方法进行比较,结果表明,相比直接进行全图目标搜索的方法,所提方法不仅准确率高、执行速度快,且检测目标的位置更加精确。