222 research outputs found

    Colorization as a Proxy Task for Visual Understanding

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    We investigate and improve self-supervision as a drop-in replacement for ImageNet pretraining, focusing on automatic colorization as the proxy task. Self-supervised training has been shown to be more promising for utilizing unlabeled data than other, traditional unsupervised learning methods. We build on this success and evaluate the ability of our self-supervised network in several contexts. On VOC segmentation and classification tasks, we present results that are state-of-the-art among methods not using ImageNet labels for pretraining representations. Moreover, we present the first in-depth analysis of self-supervision via colorization, concluding that formulation of the loss, training details and network architecture play important roles in its effectiveness. This investigation is further expanded by revisiting the ImageNet pretraining paradigm, asking questions such as: How much training data is needed? How many labels are needed? How much do features change when fine-tuned? We relate these questions back to self-supervision by showing that colorization provides a similarly powerful supervisory signal as various flavors of ImageNet pretraining.Comment: CVPR 2017 (Project page: http://people.cs.uchicago.edu/~larsson/color-proxy/

    Multi-task Self-Supervised Visual Learning

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    We investigate methods for combining multiple self-supervised tasks--i.e., supervised tasks where data can be collected without manual labeling--in order to train a single visual representation. First, we provide an apples-to-apples comparison of four different self-supervised tasks using the very deep ResNet-101 architecture. We then combine tasks to jointly train a network. We also explore lasso regularization to encourage the network to factorize the information in its representation, and methods for "harmonizing" network inputs in order to learn a more unified representation. We evaluate all methods on ImageNet classification, PASCAL VOC detection, and NYU depth prediction. Our results show that deeper networks work better, and that combining tasks--even via a naive multi-head architecture--always improves performance. Our best joint network nearly matches the PASCAL performance of a model pre-trained on ImageNet classification, and matches the ImageNet network on NYU depth prediction.Comment: Published at ICCV 201

    PCCNet:A Few-Shot Patch-wise Contrastive Colorization Network

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    Few-shot colorization aims to learn a model to colorize images with little training data. Yet, existing models often fail to keep color consistency due to ignored patch correlations of the images. In this paper, we propose PCCNet, a novel Patch-wise Contrastive Colorization Network to learn color synthesis by measuring the similarities and variations of image patches in two different aspects: inter-image and intra-image. Specifically, for inter-image, we investigate a patch-wise contrastive learning mechanism with positive and negative samples constraint to distinguish color features between patches across images. For intra-image, we explore a new intra-image correlation loss function to measure the similarity distribution which reveals structural relations between patches within an image. Furthermore, we propose a novel color memory loss that improves the accuracy of the memory module to store and retrieve data. Experiments show that our method allows the correctly saturated color to spread naturally over objects and also achieves higher scores in quantitative comparisons with related methods

    PCCNet:A Few-Shot Patch-wise Contrastive Colorization Network

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    Few-shot colorization aims to learn a model to colorize images with little training data. Yet, existing models often fail to keep color consistency due to ignored patch correlations of the images. In this paper, we propose PCCNet, a novel Patch-wise Contrastive Colorization Network to learn color synthesis by measuring the similarities and variations of image patches in two different aspects: inter-image and intra-image. Specifically, for inter-image, we investigate a patch-wise contrastive learning mechanism with positive and negative samples constraint to distinguish color features between patches across images. For intra-image, we explore a new intra-image correlation loss function to measure the similarity distribution which reveals structural relations between patches within an image. Furthermore, we propose a novel color memory loss that improves the accuracy of the memory module to store and retrieve data. Experiments show that our method allows the correctly saturated color to spread naturally over objects and also achieves higher scores in quantitative comparisons with related methods

    Deep Video Color Propagation

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    Traditional approaches for color propagation in videos rely on some form of matching between consecutive video frames. Using appearance descriptors, colors are then propagated both spatially and temporally. These methods, however, are computationally expensive and do not take advantage of semantic information of the scene. In this work we propose a deep learning framework for color propagation that combines a local strategy, to propagate colors frame-by-frame ensuring temporal stability, and a global strategy, using semantics for color propagation within a longer range. Our evaluation shows the superiority of our strategy over existing video and image color propagation methods as well as neural photo-realistic style transfer approaches.Comment: BMVC 201

    PCCNet:A Few-Shot Patch-wise Contrastive Colorization Network

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    Few-shot colorization aims to learn a model to colorize images with little training data. Yet, existing models often fail to keep color consistency due to ignored patch correlations of the images. In this paper, we propose PCCNet, a novel Patch-wise Contrastive Colorization Network to learn color synthesis by measuring the similarities and variations of image patches in two different aspects: inter-image and intra-image. Specifically, for inter-image, we investigate a patch-wise contrastive learning mechanism with positive and negative samples constraint to distinguish color features between patches across images. For intra-image, we explore a new intra-image correlation loss function to measure the similarity distribution which reveals structural relations between patches within an image. Furthermore, we propose a novel color memory loss that improves the accuracy of the memory module to store and retrieve data. Experiments show that our method allows the correctly saturated color to spread naturally over objects and also achieves higher scores in quantitative comparisons with related methods
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