502 research outputs found
Improving Robustness of TCM-based Robust Steganography with Variable Robustness
Recent study has found out that after multiple times of recompression, the
DCT coefficients of JPEG image can form an embedding domain that is robust to
recompression, which is called transport channel matching (TCM) method. Because
the cost function of the adaptive steganography does not consider the impact of
modification on the robustness, the modified DCT coefficients of the stego
image after TCM will change after recompression. To reduce the number of
changed coefficients after recompression, this paper proposes a robust
steganography algorithm which dynamically updates the robustness cost of every
DCT coefficient. The robustness cost proposed is calculated by testing whether
the modified DCT coefficient can resist recompression in every step of STC
embedding process. By adding robustness cost to the distortion cost and using
the framework of STC embedding algorithm to embed the message, the stego images
have good performance both in robustness and security. The experimental results
show that the proposed algorithm can significantly enhance the robustness of
stego images, and the embedded messages could be extracted correctly at almost
all cases when recompressing with a lower quality factor and recompression
process is known to the user of proposed algorithm.Comment: 15 pages, 5 figures, submitted to IWDW 2020: 19th International
Workshop on Digital-forensics and Watermarkin
Instance-specific and Model-adaptive Supervision for Semi-supervised Semantic Segmentation
Recently, semi-supervised semantic segmentation has achieved promising
performance with a small fraction of labeled data. However, most existing
studies treat all unlabeled data equally and barely consider the differences
and training difficulties among unlabeled instances. Differentiating unlabeled
instances can promote instance-specific supervision to adapt to the model's
evolution dynamically. In this paper, we emphasize the cruciality of instance
differences and propose an instance-specific and model-adaptive supervision for
semi-supervised semantic segmentation, named iMAS. Relying on the model's
performance, iMAS employs a class-weighted symmetric intersection-over-union to
evaluate quantitative hardness of each unlabeled instance and supervises the
training on unlabeled data in a model-adaptive manner. Specifically, iMAS
learns from unlabeled instances progressively by weighing their corresponding
consistency losses based on the evaluated hardness. Besides, iMAS dynamically
adjusts the augmentation for each instance such that the distortion degree of
augmented instances is adapted to the model's generalization capability across
the training course. Not integrating additional losses and training procedures,
iMAS can obtain remarkable performance gains against current state-of-the-art
approaches on segmentation benchmarks under different semi-supervised partition
protocols
Beyond Attentive Tokens: Incorporating Token Importance and Diversity for Efficient Vision Transformers
Vision transformers have achieved significant improvements on various vision
tasks but their quadratic interactions between tokens significantly reduce
computational efficiency. Many pruning methods have been proposed to remove
redundant tokens for efficient vision transformers recently. However, existing
studies mainly focus on the token importance to preserve local attentive tokens
but completely ignore the global token diversity. In this paper, we emphasize
the cruciality of diverse global semantics and propose an efficient token
decoupling and merging method that can jointly consider the token importance
and diversity for token pruning. According to the class token attention, we
decouple the attentive and inattentive tokens. In addition to preserving the
most discriminative local tokens, we merge similar inattentive tokens and match
homogeneous attentive tokens to maximize the token diversity. Despite its
simplicity, our method obtains a promising trade-off between model complexity
and classification accuracy. On DeiT-S, our method reduces the FLOPs by 35%
with only a 0.2% accuracy drop. Notably, benefiting from maintaining the token
diversity, our method can even improve the accuracy of DeiT-T by 0.1% after
reducing its FLOPs by 40%
Affinity Attention Graph Neural Network for Weakly Supervised Semantic Segmentation
Weakly supervised semantic segmentation is receiving great attention due to
its low human annotation cost. In this paper, we aim to tackle bounding box
supervised semantic segmentation, i.e., training accurate semantic segmentation
models using bounding box annotations as supervision. To this end, we propose
Affinity Attention Graph Neural Network (GNN). Following previous
practices, we first generate pseudo semantic-aware seeds, which are then formed
into semantic graphs based on our newly proposed affinity Convolutional Neural
Network (CNN). Then the built graphs are input to our GNN, in which an
affinity attention layer is designed to acquire the short- and long- distance
information from soft graph edges to accurately propagate semantic labels from
the confident seeds to the unlabeled pixels. However, to guarantee the
precision of the seeds, we only adopt a limited number of confident pixel seed
labels for GNN, which may lead to insufficient supervision for training.
To alleviate this issue, we further introduce a new loss function and a
consistency-checking mechanism to leverage the bounding box constraint, so that
more reliable guidance can be included for the model optimization. Experiments
show that our approach achieves new state-of-the-art performances on Pascal VOC
2012 datasets (val: 76.5\%, test: 75.2\%). More importantly, our approach can
be readily applied to bounding box supervised instance segmentation task or
other weakly supervised semantic segmentation tasks, with state-of-the-art or
comparable performance among almot all weakly supervised tasks on PASCAL VOC or
COCO dataset. Our source code will be available at
https://github.com/zbf1991/A2GNN.Comment: Accepted by IEEE Transactions on Pattern Analysis and Machine
Intelligence (TAPMI 2021
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