Jeng-Hau Lin, Atieh Lotfi, Vahideh Akhlaghi, Zhuowen Tu, and
Rajesh Gupta, "Accelerating Local Binary Pattern Networks with
Software-Programmable FPGAs", Desgin, Automation and Test in
Europe (DATE), 2019 (accepted).
Saining Xie, Chen Sun, Jonathan Huang, Zhuowen Tu, and Kevin
Murphy, "Rethinking Spatiotemporal Feature Learning: Speed-Accuracy
Trade-offs in Video Classification", ECCV, 2018.
Kwonjoon Lee, Weijian Xu, Fan Fan, and Zhuowen Tu, "Wasserstein
Introspective Neural
Networks", CVPR, 2018 (oral) (pdf).
(code)
Saining Xie*, Sainan Liu*, Zeyu Chen, and Zhuowen Tu,
"Attentional ShapeContextNet for Point Cloud Recognition", CVPR,
2018 (*equal contribution) (pdf).
Liming Zhao, Mingjie Li, Depu Meng, Xi Li, Zhaoxiang Zhang,
Yueting Zhuang, Zhuowen Tu, and Jingdong Wang,
"Deep Convolutional Neural Networks with Merge-and-Run Mappings.",
IJCAI,
2018 (pdf, code).
Long Jin, Justin Lazarow, and Zhuowen Tu, "Introspective
Classification with Convolutional Nets", NIPS 2017 (pdf).
Justin Lazarow*, Long Jin*, and Zhuowen Tu, "Introspective Neural
Networks for Generative Modeling", ICCV 2017 (*equal contribution, pdf).
(code)
Saining Xie, Ross Girshick, Piotr Dollár, Zhuowen Tu, and Kaiming
He, "Aggregated Residual Transformations for Deep Neural Networks", arXiv:1611.05431, CVPR
2017. (code)
Qibin Hou, Ming-Ming Cheng, Xiao-Wei Hu, Ali Borji, Zhuowen Tu,
and Philip Torr, "Deeply supervised salient object detection with short
connections", arXiv:1611.04849,
CVPR 2017.
Saining Xie*, Xun Huang*, and Zhuowen Tu, "Top-down Learning for
Structured Labeling with Convolutional Pseudoprior", ECCV 2016 (arXiv:1511.07409). (*equal contribution).
Ming-Ming Cheng, Yun Liu, Qibin Hou,
Jiawang Bian, Philip Torr, Shimin Hu, and Zhuowen Tu, "HFS:
Hierarchical Feature Selection
for Efficient Image Segmentation", ECCV 2016.
Jameson Merkow, David Kriegman, Alison
Marsden, and Zhuowen Tu, "Dense Volume-to-Volume Vascular Boundary
Detection", MICCAI 2016. (pdf)
Chen-Yu Lee, Patrick Gallagher, and Zhuowen
Tu, "Generalizing Pooling Functions in Convolutional Neural Networks:
Mixed, Gated, and Tree", AISTATS 2016. (arXiv:1509.08985).
Chen-Yu Lee*, Saining Xie*, Patrick
Gallagher, Zhengyou Zhang, and Zhuowen Tu, "Deeply-Supervised Nets",
AISTATS 2015. (*equal contribution) (oral
presentation at the NIPS14
Deep Learning Workshop) (pdf,
an early arxiv version) (project page).
Jameson Merkow,
Zhuowen Tu, David Kriegman, Alison Marsden, "Structural Edge Detection
for Cardiovascular Modeling", MICCAI 2015. (pdf)
Jiajun Wu, Yining Wang, Zhulin Li, and Zhuowen Tu,
"Harvesting Motion Patterns in Still Images from the Internet", CogSci
2014. (pdf)
Wei Bi, Liwei Wang, James Kwok, and Zhuowen Tu, "Learning to
Predict from Crowdsourced Data", UAI 2014. (pdf)
Jiajun Wu, Jun-Yan Zhu, and Zhuowen Tu, "Reverse Image
Segmentation: A High-Level Solution to a Low-Level Task", BMVC 2014 (pdf).
Bo Wang and Zhuowen Tu, and John Tsotsos, "Dynamic Label
Propagation for Semi-supervised Multi-class Multi-label
Classification", ICCV 2013. (pdf)
Jun Zhu, Baoyuan Wang, Xiaokang Yang, Wenjun Zhang, and Zhuowen
Tu, "Action Recognition with Actons", ICCV 2013. (pdf)
Xinggang Wang, Baoyuan Wang, Xiang Bai, Wenyu Liu, and Zhuowen
Tu, "Max-Margin Multiple Instance Dictionary Learning", International
Conference on Machine Learning (ICML), Atlanta, June, 2013. (pdf)
Quannan Li, Jingdong Wang, David Wipf, and Zhuowen Tu,
"Fixed-Point Model for Structured Labeling", International Conference
on Machine Learning (ICML), Atlanta, June, 2013. (pdf)
(matlab
source code)
Quannan Li, Jiajun Wu, and Zhuowen Tu, "Harvesting Mid-level
Visual Concepts from Large-scale Internet Images", CVPR 2013 (pdf)
(project page).
Jiayi Ma, Ji Zhao, Jinwen Tian, Zhuowen Tu, and Alan Yuille,
"Robust Estimation of Nonrigid Transformation for Point Set
Registration", CVPR 2013 (pdf).
Bo Wang and Zhuowen Tu, "Sparse Subspace
Denoising for Image Manifolds", CVPR 2013. (pdf)
Yan Xu, Jianwen Zhang, Eric Chang, Maode Lai, and Zhuowen Tu,
"Contexts-Constrained Multiple Instance Learning for Histopathology
Image Segmentation", MICCAI 2012. (pdf)
Liwei Wang, Xiong Li, Zhuowen Tu, and Jiaya Jia, "Discriminative
Clustering via Generative Feature Mapping", AAAI 2012. (pdf)
Bo Wang and Zhuowen Tu, "Affinity Learning via Self-diffusion for
Image Segmentation and Clustering", CVPR 2012. (pdf)
Bo Wang, Jiayan Jiang, Wei Wang, Zhi-Hua Zhou, and Zhuowen Tu,
"Unsupervised Metric Fusion by Cross Diffusion", CVPR 2012. (pdf)
Jun-Yan Zhu, Jiajun Wu, Yichen Wei, Eric Chang, and Zhuowen Tu,
"Unsupervised Object Class Discovery via Saliency-Guided Multiple Class
Learning", CVPR 2012. (pdf)
(project page)
Yan Xu*, Jun-Yan Zhu*, Eric Chang, and Zhuowen Tu, "Multiple
Clustered Instance Learning for Histopathology Cancer Image
Segmentation, Clustering, and Classification", CVPR 2012 (* equal
contribution). (pdf)
(code)
Cong Yao, Xiang Bai, Wenyu Liu, Yi Ma, and Zhuowen Tu, "Detecting
Texts of Arbitrary Orientations in Natural Images", CVPR 2012. (pdf)
(data)
Wei Shen, Ke Deng, Xiang Bai, Tommer Leyvand, Baining Guo, and
Zhuowen Tu, "Exemplar-Based Human Action Pose Correction and Tagging",
CVPR 2012. (pdf)
Jing Wang, Jingdong Wang, Gang Zeng, Zhuowen Tu, and Shipeng Li,
"Scalable k-NN graph construction for Visual Descriptors", CVPR 2012. (pdf)
Jiayan Jiang, Bo Wang, and Zhuowen Tu, "Unsupervised Metric
Learning by Self-Smoothing Operator", ICCV 2011. (pdf)
Yi Hong, Quannan Li, Jiayan Jiang, and Zhuowen Tu, "Learning A
Mixture of Sparse Distance Metrics for Classification and
Dimensionality Reduction", ICCV 2011. (pdf)
B. Speier, J.E. Iglesias, L. El-Kara, Z.
Tu, and C.W. Arnold. "Robust Skull Stripping of Clinical Glioblastoma
Multiforme Data'', MICCAI 2011. (pdf)
J. E. Iglesias, Jiayan Jiang, Cheng-Yi Liu,
and Zhuowen Tu, "Classification of Alzheimer's Disease Using a
Self-Smoothing Operator", MICCAI 2011. (pdf)
J. E. Iglesias, E. Konukoglu, A. Montillo,
Z. Tu, and A. Criminisi, "Combining Generative and Discriminative
Models
for Semantic Segmentation of CT Scans via Active Learning", Information Processing in Medical Imaging (IPMI),
July, 2011.
Xiang Bai, Bo Wang, Xinggang Wang, Wenyu Liu, and Zhuowen Tu,
"Co-Transduction for Shape Retrieval", ECCV 2010. (pdf)
Bo Wang, Xiang Bai, Xinggang Wang, Wenyu Liu, and Zhuowen Tu,
"Object Recognition Using Junctions", ECCV 2010. (pdf)
Juan Eugenio Iglesias, Cheng-Yi Liu, Paul
Thompson, and Zhuowen Tu, "Agreement-Based Semi-Supervised Learning for
Skull Stripping", MICCAI, 2010. (pdf)
Juan Eugenio Iglesias, Ivo Dinov, Jaskaran
Singh, Gregory Tong, and Zhuowen Tu, "Synthetic
MRI signal standardization: application to multi-atlas analysis",
MICCAI,
2010. (pdf)
Xiang Bai, Xinggang
Wang, Wenyu Liu, Longin Jan Latecki, and Zhuowen Tu, "Active Skeleton for
Non-rigid Object Detection", ICCV 2009 (pdf).
Jiayan Jiang and Zhuowen Tu, "Efficient Scale
Space Auto-context for Image Segmentation and Labeling", CVPR 2009 (pdf).
Xiang Bai, Quannan Li, Longin Jan Latecki,
Wenyu Liu, and Zhuowen Tu,
"Shape Band: A Deformable Object Detection Approach", CVPR 2009(pdf).
Piotr Dollár, Zhuowen Tu, Pietro Perona, and Serge Belongie, "Integral
Channel Features", Proc. of British Machine Vision Conference (BMVC),
2009 (pdf).
Zhuowen
Tu, "Auto-context and Its Application to High-level Vision
Tasks", CVPR, 2008 (pdf). (now matlab
code included in the fixed point package)
Jiayan Jiang, Songfeng Zheng, Arthur Toga,
and Zhuowen Tu,
"Learning
Based Coarse-to-fine Image Registration", CVPR 2008 (pdf).
Jason Corso, Alan Yuille, and Zhuowen Tu, "Graph-Shifts:
Natural Images Labeling by Dynamic Hierarchical Computing", CVPR 2008 (pdf).
Xingwei Yang, Xiang Bai, Longin Jan
Latecki, and Zhuowen Tu,
"Improving Shape Retrieval by Learning Graph Transduction", ECCV 2008 (pdf).
Piotr Dollár, Boris Babenko, Serge Belongie, Pietro Perona, and Zhuowen Tu, "Multiple Component
Learning for Object Detection", ECCV 2008 (pdf).
Zhuowen
Tu, "Learning Generative Models via Discriminative
Approaches", IEEE Computer Vision and Pattern Recognition (CVPR), June,
2007. (pdf)
Songfeng Zheng, Zhuowen Tu, and Alan Yuille,
"Detecting Object Boundaries Using Low-, Mid-, and High-Level
Information", IEEE Computer Vision and Pattern Recognition (CVPR),
June, 2007. (pdf)
Piotr Dollár, Zhuowen Tu,
Hai Tao and Serge Belongie, "Feature Mining for Image Classification",
IEEE Computer Vision and Pattern Recognition (CVPR), June, 2007. (pdf)
Jason Corso, Zhuowen Tu, Alan Yuille, and
Arthur Toga, "Likelihood Shift Graphs for Efficient Energy
Minimization", Information Processing in Medical Imaging (IPMI), June,
2007. (pdf)
Zhuowen
Tu, Xiang Sean Zhou, Adrian Barbu, Luca Bogoni, and Dorin
Comaniciu, "Probabilistic 3D Polyp Detection in CT Images: The Role of
Sample Alignment", IEEE Computer Vision and Pattern Recognition (CVPR),
June, 2006. (pdf)
Piotr Dollár, Zhuowen Tu,
and Serge Belongie, "Supervised Learning of Edges and Object
Boundaries", IEEE Computer Vision and Pattern Recognition (CVPR), June,
2006. (pdf)
Zhuowen
Tu, Xiang Sean Zhou, Dorin Comaniciu, and Luca Bogoni, "A
Learning Based Approach for 3D Segmentation and Colon Detagging", 9th
European Conf. on Computer Vision (ECCV), May 2006. (pdf)
Zhuowen
Tu, "An Integrated Frmework for Image Segmentation and
Perceptual Grouping", 10th IEEE International Conference on Computer
Vision (ICCV), Oct.
2005 (pdf).
Zhuowen
Tu, "Probabilistic Boosting-Tree: Learning Discriminative
Models for Classification, Recognition, and Clustering", 10th IEEE
International Conf. on Computer Vision (ICCV), Oct. 2005 (pdf).
Zhuowen
Tu, and Alan Yuille "Shape Matching and Recognition--Using
Generative Models and Informative Features", 8th European Conf. on
Computer Vision (ECCV), May 2004 (pdf).
Zhuowen
Tu, Xiangrong Chen, Alan Yuille, and Song-Chun Zhu, "Image
Parsing: Segmentation, Detection, and Object Recognition", 9th IEEE
International Conf.
on Computer Vision (ICCV), Oct. 2003 (Marr Prize). (pdf).
Zhuowen
Tu and Song-Chun Zhu, "Parsing Images into Region and Curve
Processes", 7th European Conf. on Computer Vision (ECCV), May, 2002. (pdf)
Feng Han, Zhuowen Tu, and Song-Chun Zhu,
"A Stochastic
Algorithm for Parsing and reconstructing 3D Scenes", 7th European Conf.
on
Computer Vision (ECCV), May, 2002. (pdf)
Zhuowen
Tu, Song-Chun Zhu, and Harry Shum, "Image Segmentation by Data
Driven Markov Chain Monte Carlo", 8th IEEE International Conf. on
Computer
Vision (ICCV), July 2001. (pdf)
Song-Chun Zhu, Rong Zhang, and Zhuowen Tu, "Integrating
Top-down/Bottom-up for Object Recognition by Data Driven Markov Chain
Monte Carlo", IEEE Computer Vision and Pattern Recognition (CVPR), July
2000. (pdf)
Journals
Qibin Hou, Ming-Ming Cheng, Xiaowei Hu, Ali Borji, Zhuowen Tu,
Philip H. S. Torr, "Deeply Supervised Salient Object Detection with
Short Connections", IEEE Trans. on Pattern
Analysis and Machine Intelligence (accepted), 2018.
Chen-Yu Lee, Patrick Gallagher, and Zhuowen Tu, "Generalizing
Pooling Functions in Convolutional Neural Networks: Mixed, Gated, and
Tree", IEEE Trans. on Pattern Analysis and
Machine Intelligence, vol. 40, no 4, pp. 863-875, May, 2017. (pdf)
Saining Xie and Zhuowen Tu, "Holistically-Nested Edge Detection",
International Journal of Computer Vision, 125(1-3): 3-18, 2017. (pdf)
Jun-Yan Zhu, Jiajun Wu, Yan Xu, Eric Chang, and Zhuowen Tu,
"Unsupervised Object Class Discovery via Saliency-Guided Multiple Class
Learning", IEEE Trans. on Pattern Analysis and
Machine Intelligence, vol. 37, no. 4, pp. 862-875, April, 2015. (pdf)
(project
page).
B. Wang, A. Mezlini, F. Demir, M. Fiume, Z. Tu, M. Brudno, B.
Haibe-Kains, and A.
Goldenberg, "Similarity Network Fusion for Aggregating Data
Types on a Genomic Scale". Nature Methods,
doi:10.1038/nmeth.2810, Jan. 2014. (link)
Yan Xu, Jun-Yan Zhu, Eric I-Chao Chang, Maode Lai, and Zhuowen
Tu, "Weakly Supervised Histopathology Cancer Image Segmentation and
Classification", Medical Image Analysis, 2014. (pdf)
(project
page) (code)
Xinggang Wang, Zhengdong Zhang, Yi Ma, Xiang Bai, Wenyu Liu, and
Zhuowen Tu, "Robust Subspace Discovery via Relaxed Rank Minimization",
Neural
Computation, 2014 (pdf).
Jiayi Ma, Ji Zhao, Jianwen Tian, Xiang Bai, and Zhuowen Tu, "Regularized Vector
Field Learning
with Sparse Approximation for Mismatch Removal", Pattern Recognition
2013.
Cong Yao, Xin Zhang, Xiang Bai, Wenyu Liu, Yi Ma, Zhuowen Tu, "Rotation-invariant
Features for Multi-oriented Text Detection in Natural Images", Plos
One, August 5, 2013.
Cheng-Yi Liu, Juan Eugenio Iglesias, and Zhuowen Tu, "Integrated Deformable
Templates and Discriminative Models for Robust 3D Brain MRI
Segmentation", Neuroinformatics, 2013 (in press).
Huazhu Fu, Xiaochun Cao, and Zhuowen
Tu, "Cluster-based Co-saliency Detection", IEEE Tran. on Image
Processing, 2013 (pdf)
.
Y Xu, Y Wang, J Liu, Z Tu,
JT Sun, J Tsujii, E Chang, "Suicide note sentiment classification: a
supervised approach augmented by web data", Biomedical informatics
insights 5 (Suppl. 1), 31, 2012.
Yan Xu, Jiahua Liu, Jiajun Wu, Yue Wang, Zhuowen Tu, Jian-Tao Sun, Junichi
Tsujii, Eric Chang, "A Classification Approach to Coreference in
Discharge Summaries: 2011 I2b2 Challenge", J. of the American Medical
Informatics Association, doi:10.1136/amiajnl-2011-000734, 2012.
Xiang Bai, Bo Wang, Cong Yao, Wenyu Liu, and Zhuowen Tu, "Co-Transduction for
Shape Retrieval", IEEE Trans. on Image Processing, vol. 21, no. 5, pp.
2747-2757, May, 2012. (pdf)
Juan Eugenio Iglesias, Paul M. Thompson, Chen-Yi Liu and Zhuowen Tu, "Fast Approximate
Stochastic Tractography", Neuroinformatics, 10(1): 5-17, Jan. 2012. (pdf)
Juan Eugenio Iglesias, Chen-Yi Liu, Paul M. Thompson, and Zhuowen Tu, "Robust Brain Extraction
Across Datasets and Comparison with Publicly Available Methods", IEEE Trans. on Medical Imaging, vol. 30, no. 9,
pp. 1617-34, Sept., 2011. (pdf)
(software)
Juan Eugenio Iglesias, Paul M. Thompson, and Zhuowen Tu, "Modeling
diffusion-weighted MRI as a spatially-variant Gaussian mixture:
application to image denoising", Medical Physics, vol. 38, no. 7, pp.
4350-43064, July, 2011. (pdf)
S. G Costafreda, I. D Dinov, Z.
Tu, Y. Shi, C.-Y. Liu, I. Kloszewska, P. Mecocci, H. Soininen,
M.
Tsolaki, B. Vellas, L.-O. Wahlund, C. Spenger, A. W Toga, S. Lovestone,
A.
Simmons, "Automated hippocampal shape analysis predicts the onset of
dementia
in mild cognitive impairment", NeuroImage, Jan. 2011. (pdf)
Songfeng Zheng, Alan Yuille, and Zhuowen
Tu, "Detecting Object Boundaries Using Low-, Mid-, and
High-Level Information", Journal of
Computer Vision and Image Understanding,
vol. 114, no. 19, Oct. 2010.
(pdf)
Zhuowen Tu and Xiang Bai,
"Auto-context and Its Application to High-level Vision Tasks and 3D
Brain
Image Segmentation", IEEE Trans. on
Pattern
Analysis and Machine Intelligence, vol. 21, no. 10, pp. 1744-1757, 2010. (pdf)
Jonathan H. Morra, Zhuowen Tu,
Liana G. Apostolova, Amity Green, Arthur W. Toga, and Paul M. Thompson,
"Comparison of AdaBoost and Support Vector Machines for Detecting
Alzheimer's
Disease through Automated Hippocampal Segmentation, IEEE Trans. on
Medical
Imaging, vol. 29, no. 1, pp. 30-43, Jan. 2010 (pdf).
Xiang Bai, Xingwei Yang, Longin Jan
Latecki, Wenyu Liu, and Zhuowen Tu, "Learning Context
Sensitive Shape Similarity by Graph Transduction", IEEE Trans. on
Pattern Analysis and Machine Intelligence, vol. 32, no. 5, pp. 861-874,
May, 2010. (pdf)
S. Fears, W. Melega, S. K. Service, C. Lee,
K. Chen, Z. Tu, M. J. Jorgensen, L. A. Fairbanks, N.
Freimer, R. P. Woods, "Identifying Heritable Brain Phenotypes in an
Extended Pedigree of Vervet Monkeys”, Journal of Neuroscience, vol. 29,
no. 9, pp. 2867-2875, 2009. (pdf)
Y. Shi, Z. Tu, A. L.
Reiss, R. Dutton, A. Lee, A.M. Galaburda, I. Dinov, P. Thompson, A.
Toga, "Joint Sulcal Detection on Cortical Surfaces with Graphical
Models and Boosted Priors", IEEE Trans. on Medical Imaging, vol. 28,
no. 3, pp. 361-373, 2009. (pdf)
J. H. Morra, Z. Tu, L. G.
Apostolova, A. E. Greena, C. Avedissiana, S. K. Madsen, N. Parikshak,
X.
Hua, A. W. Toga, C. R. JackJrc, M. W. Weiner, P. M. Thompson,
"Validation
of a Fully Automated 3D Hippocampal Segmentation Method Using Subjects
with
Alzheimer's Disease, Mild Cognitive Impairment, and Elderly Controls",
NeuroImge,
Oct. 15; (43(1), pp. 59-68, 2008. (pdf)
Zhuowen Tu, Katherin Narr,
Piotr Dollar, Iov Dinov, Paul Thompson, and Arthur Toga, "Brain
Anatomical
Structure Segmentation by Hybrid Discriminative/Generative Models",
IEEE
Trans. on Medical Imaging, vol. 27, no. 4, pp. 495-508, April, 2008. (pdf)
Zhuowen Tu, Songfeng
Zheng, and Alan Yuille, "Shape Matching and Registration by Data-driven
EM", Journal of Computer Vision and Image Understanding, vol. 109, pp.
290-304, 2008. (pdf)
Y. Shi, P. M. Thompson, G. I. De Zubicaray,
S. E. Rose, Z. Tu, I. Dinov, and A. Toga, "Direct
Mapping
of Hippocampal surfaces with Intrinsic Shape Context", Neuroimage, vol.
37, no. 3, pp. 792-807, Sep., 2007.
Z. Tu, S. Zheng, , A.
Yuille, A. Reiss, R. Dutton, A.Lee, A.Galaburda, I. Dinov, P. Thompson,
A. Toga, "Automated
Extraction of the Cortical Sulci Based on a Supervised Learning
Approach",
IEEE Trans. on Medical Imaging, vol. 26, no. 4, April, pp. 541-552,
2007.
(pdf)
Zhuowen Tu and Song-Chun
Zhu, "Parsing Images into Regions, Curves, and Curve Groups",
International Journal of Computer Vision, vol. 69, no. 2, pp. 223-249,
Aug., 2006. (pdf)
Zhuowen Tu, Xiangrong
Chen, Alan Yuille, and Song-Chun Zhu, "Image Parsing: Unifying
Segmentation, Detection, and Object Recognition", International Journal
of Computer Vision, vol. 63, no. 2, pp. 113-140, July, 2005. (pdf)
Feng Han, Zhuowen Tu, and
Song-Chun Zhu, "Range Image Segmentation by an Efficient Jump-Diffusion
Method",
IEEE Trans. on Pattern Analysis and Machine Intelligence, vol. 26, no.
9,
pp. 1138-1153, Sept. 2004. (pdf)
Zhuowen Tu and Song-Chun
Zhu, "Image Segmentation by Data-Driven Markov Chain Monte Carlo", IEEE
Trans. on Pattern Analysis and Machine Intelligence, Vol. 24, No. 5,
pp. 657-673,May, 2002. (pdf)
Zhuowen Tu and Ronxing Li,
"A Framework for Automatic Recognition of Spatial Features from Mobile
Mapping Imagery", Journal of Photogrammetric Engineering and Remote
Sensing, Vol. 68, No. 3, March, 2002.
Other Refereed Conferences and Workshops
Weichao Qiu, Xinggang Wang, Xiang Bai, Alan Yuille, and Zhuowen
Tu, "Scale-Space Sift Flow", Proc. of WACV, 2014 (pdf).
Boris Babenko, Piotr
Dollár, Zhuowen
Tu, and Serge Belongie, "Simultaneous Learning and Alignment:
Multi-Instance
and Multi-Pose Learning", RealFaces, Marseille, France, 2008. (pdf)