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Author (up) Xavier Otazu; Maria Vanrell edit  openurl
Title Perceptual representation of textured images Type Journal
Year 2005 Publication Journal of Imaging Science and Technology, 49(3):262–271 (IF: 0.522) Abbreviated Journal  
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Notes CIC Approved no  
Call Number CAT @ cat @ OtV2005b Serial 542  
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Author (up) Xavier Otazu; Maria Vanrell edit  openurl
Title A surround-induction function to unify assimilation and contrast in a computational model of color apearance Type Miscellaneous
Year 2005 Publication Perception supplement, ECVP05 Abstracts, 34: 215 Abbreviated Journal  
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Notes CIC Approved no  
Call Number CAT @ cat @ OtV2005a Serial 568  
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Author (up) Xavier Otazu; Maria Vanrell edit  openurl
Title Several lightness induction effects with a computational multiresolution wavelet framework Type Journal
Year 2006 Publication 29th European Conference on Visual Perception (ECVP’06), Perception Suppl s, 32: 56–56 Abbreviated Journal  
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Address Saint-Petersburg (Russia)  
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Notes CIC Approved no  
Call Number CAT @ cat @ OtV2006 Serial 659  
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Author (up) Xavier Otazu; Maria Vanrell; C. Alejandro Parraga edit  openurl
Title Mutiresolution Wavelet Framework Reproduces Induction Effects Type Journal
Year 2007 Publication Perception 36:167–167, supp Abbreviated Journal  
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Notes CIC Approved no  
Call Number CAT @ cat @ OVP2007 Serial 842  
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Author (up) Xavier Otazu; Maria Vanrell; C. Alejandro Parraga edit  openurl
Title Multiresolution Wavelet Framework Models Brightness Induction Effects Type Journal
Year 2008 Publication Vision Research Abbreviated Journal VR  
Volume 48 Issue 5 Pages 733–751  
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Notes CIC Approved no  
Call Number CAT @ cat @ OVP2008a Serial 927  
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Author (up) Xavier Otazu; Maria Vanrell; C. Alejandro Parraga edit  openurl
Title Colour induction effects are modelled by a low-level multiresolution wavelet framework Type Journal
Year 2008 Publication Perception 37(Suppl.): 107 Abbreviated Journal  
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Notes CIC Approved no  
Call Number CAT @ cat @ OVP2008b Serial 1055  
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Author (up) Xavier Otazu; Olivier Penacchio; Laura Dempere-Marco edit   pdf
url  openurl
Title An investigation into plausible neural mechanisms related to the the CIWaM computational model for brightness induction Type Conference Article
Year 2012 Publication 2nd Joint AVA / BMVA Meeting on Biological and Machine Vision Abbreviated Journal  
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Abstract Brightness induction is the modulation of the perceived intensity of an area by the luminance of surrounding areas. From a purely computational perspective, we built a low-level computational model (CIWaM) of early sensory processing based on multi-resolution wavelets with the aim of replicating brightness and colour (Otazu et al., 2010, Journal of Vision, 10(12):5) induction effects. Furthermore, we successfully used the CIWaM architecture to define a computational saliency model (Murray et al, 2011, CVPR, 433-440; Vanrell et al, submitted to AVA/BMVA'12). From a biological perspective, neurophysiological evidence suggests that perceived brightness information may be explicitly represented in V1. In this work we investigate possible neural mechanisms that offer a plausible explanation for such effects. To this end, we consider the model by Z.Li (Li, 1999, Network:Comput. Neural Syst., 10, 187-212) which is based on biological data and focuses on the part of V1 responsible for contextual influences, namely, layer 2-3 pyramidal cells, interneurons, and horizontal intracortical connections. This model has proven to account for phenomena such as visual saliency, which share with brightness induction the relevant effect of contextual influences (the ones modelled by CIWaM). In the proposed model, the input to the network is derived from a complete multiscale and multiorientation wavelet decomposition taken from the computational model (CIWaM).
This model successfully accounts for well known pyschophysical effects (among them: the White's and modied White's effects, the Todorovic, Chevreul, achromatic ring patterns, and grating induction effects) for static contexts and also for brigthness induction in dynamic contexts defined by modulating the luminance of surrounding areas. From a methodological point of view, we conclude that the results obtained by the computational model (CIWaM) are compatible with the ones obtained by the neurodynamical model proposed here.		  
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Area Expedition Conference AV A  
Notes CIC Approved no  
Call Number Admin @ si @ OPD2012a Serial 2132  
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Author (up) Xavier Otazu; Olivier Penacchio; Laura Dempere-Marco edit   pdf
doi  openurl
Title Brightness induction by contextual influences in V1: a neurodynamical account Type Abstract
Year 2012 Publication Journal of Vision Abbreviated Journal VSS  
Volume 12 Issue 9 Pages  
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Abstract Brightness induction is the modulation of the perceived intensity of an area by the luminance of surrounding areas and reveals fundamental properties of neural organization in the visual system. Several phenomenological models have been proposed that successfully account for psychophysical data (Pessoa et al. 1995, Blakeslee and McCourt 2004, Barkan et al. 2008, Otazu et al. 2008).
Neurophysiological evidence suggests that brightness information is explicitly represented in V1 and neuronal response modulations have been observed followingluminance changes outside their receptive fields (Rossi and Paradiso, 1999).
In this work we investigate possible neural mechanisms that offer a plausible explanation for such effects. To this end, we consider the model by Z.Li (1999) which is based on biological data and focuses on the part of V1 responsible for contextual influences, namely, layer 2–3 pyramidal cells, interneurons, and horizontal intracortical connections. This model has proven to account for phenomena such as contour detection and preattentive segmentation, which share with brightness induction the relevant effect of contextual influences. In our model, the input to the network is derived from a complete multiscale and multiorientation wavelet decomposition which makes it possible to recover an image reflecting the perceived intensity. The proposed model successfully accounts for well known pyschophysical effects (among them: the White's and modified White's effects, the Todorović, Chevreul, achromatic ring patterns, and grating induction effects). Our work suggests that intra-cortical interactions in the primary visual cortex could partially explain perceptual brightness induction effects and reveals how a common general architecture may account for several different fundamental processes emerging early in the visual pathway.		  
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Notes CIC Approved no  
Call Number Admin @ si @ OPD2012b Serial 2178  
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Author (up) Xavier Otazu; Olivier Penacchio; Xim Cerda-Company edit  url
openurl 
Title Brightness and colour induction through contextual influences in V1 Type Conference Article
Year 2015 Publication Scottish Vision Group 2015 SGV2015 Abbreviated Journal  
Volume 12 Issue 9 Pages 1208-2012  
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Address Carnoustie; Scotland; March 2015  
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Area Expedition Conference SGV  
Notes NEUROBIT;CIC Approved no  
Call Number Admin @ si @ OPC2015a Serial 2632  
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Author (up) Xavier Otazu; Olivier Penacchio; Xim Cerda-Company edit  openurl
Title An excitatory-inhibitory firing rate model accounts for brightness induction, colour induction and visual discomfort Type Conference Article
Year 2015 Publication Barcelona Computational, Cognitive and Systems Neuroscience Abbreviated Journal  
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Address Barcelona; June 2015  
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Area Expedition Conference BARCCSYN  
Notes NEUROBIT;CIC Approved no  
Call Number Admin @ si @ OPC2015b Serial 2634  
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Author (up) Xavier Otazu; Oriol Pujol edit  doi
openurl 
Title Wavelet based approach to cluster analysis. Application on low dimensional data sets Type Journal Article
Year 2006 Publication Pattern Recognition Letters Abbreviated Journal PRL  
Volume 27 Issue 14 Pages 1590–1605  
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Notes MILAB; CIC; HuPBA Approved no  
Call Number BCNPCL @ bcnpcl @ OtP2006 Serial 658  
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Author (up) Xavier Roca; Jordi Vitria; Maria Vanrell; Juan J. Villanueva edit  openurl
Title Visual behaviours for binocular navigation with autonomous systems. Type Miscellaneous
Year 1999 Publication Proceedings of the VIII Symposium Nacional de Reconocimiento de Formas y Analisis de Imagenes Abbreviated Journal  
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Address Bilbao  
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Notes OR;ISE;CIC;MV Approved no  
Call Number BCNPCL @ bcnpcl @ RVV1999a Serial 13  
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Author (up) Xavier Roca; Jordi Vitria; Maria Vanrell; Juan J. Villanueva edit  openurl
Title Gaze control in a binocular robot systems Type Miscellaneous
Year 1999 Publication Abbreviated Journal  
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Address Barcelona  
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Notes OR;ISE;CIC;MV Approved no  
Call Number BCNPCL @ bcnpcl @ RVV1999b Serial 41  
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Author (up) Xavier Roca; Jordi Vitria; Maria Vanrell; Juan J. Villanueva edit  openurl
Title Visual behaviours for binocular navigation with autonomous systems. Type Miscellaneous
Year 2000 Publication Pattern Recognition and Applications, IOS Press, 134–143. Abbreviated Journal  
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Notes OR;ISE;CIC;MV Approved no  
Call Number BCNPCL @ bcnpcl @ RVV2000 Serial 245  
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Author (up) Xim Cerda-Company; C. Alejandro Parraga; Xavier Otazu edit  openurl
Title Which tone-mapping is the best? A comparative study of tone-mapping perceived quality Type Abstract
Year 2014 Publication Perception Abbreviated Journal  
Volume 43 Issue Pages 106  
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Abstract Perception 43 ECVP Abstract Supplement
High-dynamic-range (HDR) imaging refers to the methods designed to increase the brightness dynamic range present in standard digital imaging techniques. This increase is achieved by taking the same picture under di erent exposure values and mapping the intensity levels into a single image by way of a tone-mapping operator (TMO). Currently, there is no agreement on how to evaluate the quality
of di erent TMOs. In this work we psychophysically evaluate 15 di erent TMOs obtaining rankings based on the perceived properties of the resulting tone-mapped images. We performed two di erent experiments on a CRT calibrated display using 10 subjects: (1) a study of the internal relationships between grey-levels and (2) a pairwise comparison of the resulting 15 tone-mapped images. In (1) observers internally matched the grey-levels to a reference inside the tone-mapped images and in the real scene. In (2) observers performed a pairwise comparison of the tone-mapped images alongside the real scene. We obtained two rankings of the TMOs according their performance. In (1) the best algorithm
was ICAM by J.Kuang et al (2007) and in (2) the best algorithm was a TMO by Krawczyk et al (2005). Our results also show no correlation between these two rankings.		  
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Area Expedition Conference ECVP  
Notes CIC; NEUROBIT; 600.074 Approved no  
Call Number Admin @ si @ CPO2014 Serial 2527  
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Author (up) Yasuko Sugito; Trevor Canham; Javier Vazquez; Marcelo Bertalmio edit  url
doi  openurl
Title A Study of Objective Quality Metrics for HLG-Based HDR/WCG Image Coding Type Journal
Year 2021 Publication SMPTE Motion Imaging Journal Abbreviated Journal SMPTE  
Volume 130 Issue 4 Pages 53 - 65  
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Abstract In this work, we study the suitability of high dynamic range, wide color gamut (HDR/WCG) objective quality metrics to assess the perceived deterioration of compressed images encoded using the hybrid log-gamma (HLG) method, which is the standard for HDR television. Several image quality metrics have been developed to deal specifically with HDR content, although in previous work we showed that the best results (i.e., better matches to the opinion of human expert observers) are obtained by an HDR metric that consists simply in applying a given standard dynamic range metric, called visual information fidelity (VIF), directly to HLG-encoded images. However, all these HDR metrics ignore the chroma components for their calculations, that is, they consider only the luminance channel. For this reason, in the current work, we conduct subjective evaluation experiments in a professional setting using compressed HDR/WCG images encoded with HLG and analyze the ability of the best HDR metric to detect perceivable distortions in the chroma components, as well as the suitability of popular color metrics (including ΔITPR , which supports parameters for HLG) to correlate with the opinion scores. Our first contribution is to show that there is a need to consider the chroma components in HDR metrics, as there are color distortions that subjects perceive but that the best HDR metric fails to detect. Our second contribution is the surprising result that VIF, which utilizes only the luminance channel, correlates much better with the subjective evaluation scores than the metrics investigated that do consider the color components.  
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Notes CIC Approved no  
Call Number SCV2021 Serial 3671  
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Author (up) Yawei Li; Yulun Zhang; Radu Timofte; Luc Van Gool; Zhijun Tu; Kunpeng Du; Hailing Wang; Hanting Chen; Wei Li; Xiaofei Wang; Jie Hu; Yunhe Wang; Xiangyu Kong; Jinlong Wu; Dafeng Zhang; Jianxing Zhang; Shuai Liu; Furui Bai; Chaoyu Feng; Hao Wang; Yuqian Zhang; Guangqi Shao; Xiaotao Wang; Lei Lei; Rongjian Xu; Zhilu Zhang; Yunjin Chen; Dongwei Ren; Wangmeng Zuo; Qi Wu; Mingyan Han; Shen Cheng; Haipeng Li; Ting Jiang; Chengzhi Jiang; Xinpeng Li; Jinting Luo; Wenjie Lin; Lei Yu; Haoqiang Fan; Shuaicheng Liu; Aditya Arora; Syed Waqas Zamir; Javier Vazquez; Konstantinos G. Derpanis; Michael S. Brown; Hao Li; Zhihao Zhao; Jinshan Pan; Jiangxin Dong; Jinhui Tang; Bo Yang; Jingxiang Chen; Chenghua Li; Xi Zhang; Zhao Zhang; Jiahuan Ren; Zhicheng Ji; Kang Miao; Suiyi Zhao; Huan Zheng; YanYan Wei; Kangliang Liu; Xiangcheng Du; Sijie Liu; Yingbin Zheng; Xingjiao Wu; Cheng Jin; Rajeev Irny; Sriharsha Koundinya; Vighnesh Kamath; Gaurav Khandelwal; Sunder Ali Khowaja; Jiseok Yoon; Ik Hyun Lee; Shijie Chen; Chengqiang Zhao; Huabin Yang; Zhongjian Zhang; Junjia Huang; Yanru Zhang edit  url
doi  openurl
Title NTIRE 2023 challenge on image denoising: Methods and results Type Conference Article
Year 2023 Publication Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition Workshops Abbreviated Journal  
Volume Issue Pages 1904-1920  
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Abstract This paper reviews the NTIRE 2023 challenge on image denoising (σ = 50) with a focus on the proposed solutions and results. The aim is to obtain a network design capable to produce high-quality results with the best performance measured by PSNR for image denoising. Independent additive white Gaussian noise (AWGN) is assumed and the noise level is 50. The challenge had 225 registered participants, and 16 teams made valid submissions. They gauge the state-of-the-art for image denoising.  
Address Vancouver; Canada; June 2023  
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Area Expedition Conference CVPRW  
Notes MACO; CIC Approved no  
Call Number Admin @ si @ LZT2023 Serial 3910  
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