SimCLR¶

A Simple Framework for Contrastive Learning of Visual Representations

Abstract¶

This paper presents SimCLR: a simple framework for contrastive learning of visual representations. We simplify recently proposed contrastive self-supervised learning algorithms without requiring specialized architectures or a memory bank. In order to understand what enables the contrastive prediction tasks to learn useful representations, we systematically study the major components of our framework. We show that (1) composition of data augmentations plays a critical role in defining effective predictive tasks, (2) introducing a learnable nonlinear transformation between the representation and the contrastive loss substantially improves the quality of the learned representations, and (3) contrastive learning benefits from larger batch sizes and more training steps compared to supervised learning. By combining these findings, we are able to considerably outperform previous methods for self-supervised and semi-supervised learning on ImageNet. A linear classifier trained on self-supervised representations learned by SimCLR achieves 76.5% top-1 accuracy, which is a 7% relative improvement over previous state-of-the-art, matching the performance of a supervised ResNet-50.

Results and Models¶

In this page, we provide benchmarks as much as possible to evaluate our pre-trained models. If not mentioned, all models are pre-trained on ImageNet-1k dataset.

Classification¶

The classification benchmarks includes 4 downstream task datasets, VOC, ImageNet, iNaturalist2018 and Places205. If not specified, the results are Top-1 (%).

VOC SVM / Low-shot SVM¶

The Best Layer indicates that the best results are obtained from which layers feature map. For example, if the Best Layer is feature3, its best result is obtained from the second stage of ResNet (1 for stem layer, 2-5 for 4 stage layers).

Besides, k=1 to 96 indicates the hyper-parameter of Low-shot SVM.

Self-Supervised Config	Best Layer	SVM	k=1	k=2	k=4	k=8	k=16	k=32	k=64	k=96
resnet50_8xb32-coslr-200e	feature5	79.98	35.02	42.79	54.87	61.91	67.38	71.88	75.56	77.4

ImageNet Linear Evaluation¶

The Feature1 - Feature5 don’t have the GlobalAveragePooling, the feature map is pooled to the specific dimensions and then follows a Linear layer to do the classification. Please refer to resnet50_mhead_linear-8xb32-steplr-90e_in1k for details of config.

Self-Supervised Config	Feature1	Feature2	Feature3	Feature4	Feature5
resnet50_8xb32-coslr-200e	16.29	31.11	39.99	55.06	62.91
resnet50_16xb256-coslr-200e	15.44	31.47	41.83	59.44	66.41

Algorithm	Backbone	Epoch	Batch Size	Results (Top-1 %)		Links
Algorithm	Backbone	Epoch	Batch Size	Linear Eval	Fine-tuning	Pretrain	Linear Eval	Fine-tuning
SimCLR	ResNet50	200	256	62.7	/	config \| model \| log	config \| model \| log	/
	ResNet50	200	4096	66.9	/	config \| model \| log	config \| model \| log	/
	ResNet50	800	4096	69.2	/	config \| model \| log	config \| model \| log	/

Places205 Linear Evaluation¶

The Feature1 - Feature5 don’t have the GlobalAveragePooling, the feature map is pooled to the specific dimensions and then follows a Linear layer to do the classification. Please refer to resnet50_mhead_8xb32-steplr-28e_places205.py for details of config.

Self-Supervised Config	Feature1	Feature2	Feature3	Feature4	Feature5
resnet50_8xb32-coslr-200e	20.60	33.62	38.86	45.25	50.91

ImageNet Nearest-Neighbor Classification¶

The results are obtained from the features after GlobalAveragePooling. Here, k=10 to 200 indicates different number of nearest neighbors.

Self-Supervised Config	k=10	k=20	k=100	k=200
resnet50_8xb32-coslr-200e	47.8	48.4	46.7	45.2

Detection¶

The detection benchmarks includes 2 downstream task datasets, Pascal VOC 2007 + 2012 and COCO2017. This benchmark follows the evluation protocols set up by MoCo.

Pascal VOC 2007 + 2012¶

Please refer to config for details.

Self-Supervised Config	AP50
resnet50_8xb32-coslr-200e	79.38

COCO2017¶

Please refer to config for details.

Self-Supervised Config	mAP(Box)	AP50(Box)	AP75(Box)	mAP(Mask)	AP50(Mask)	AP75(Mask)
resnet50_8xb32-coslr-200e	38.7	58.1	42.4	34.9	55.3	37.5

Segmentation¶

The segmentation benchmarks includes 2 downstream task datasets, Cityscapes and Pascal VOC 2012 + Aug. It follows the evluation protocols set up by MMSegmentation.

Pascal VOC 2012 + Aug¶

Please refer to config for details.

Self-Supervised Config	mIOU
resnet50_8xb32-coslr-200e	64.03

Citation¶

@inproceedings{chen2020simple,
  title={A simple framework for contrastive learning of visual representations},
  author={Chen, Ting and Kornblith, Simon and Norouzi, Mohammad and Hinton, Geoffrey},
  booktitle={ICML},
  year={2020},
}