Dynamic data pruning accelerates deep learning by selectively omitting less informative samples during training. While per-sample loss is a common importance metric, obtaining it can be challenging or infeasible for complex models or loss functions, often requiring significant implementation effort. This work proposes the Batch Loss Score (BLS), a computationally efficient alternative using an Exponential Moving Average (EMA) of readily available batch losses to assign scores to individual samples. We frame the batch loss, from the perspective of a single sample, as a noisy measurement of its scaled individual loss, with noise originating from stochastic batch composition. It is formally shown that the EMA mechanism functions as a first-order low-pass filter, attenuating high-frequency batch composition noise. This yields a score approximating the smoothed and persistent contribution of the individual sample to the loss, providing a theoretical grounding for BLS as a proxy for sample importance. BLS demonstrates remarkable code integration simplicity (three-line injection) and readily adapts existing per-sample loss-based methods (one-line proxy). Its effectiveness is demonstrated by enhancing two such methods to losslessly prune 20%-50% of samples across 14 datasets, 11 tasks and 18 models, highlighting its utility and broad applicability, especially for complex scenarios where per-sample loss is difficult to access. Code is available at https://github.com/mrazhou/BLS.
Table 1: BLS effectively proxies per-sample loss methods (InfoBatch, SeTa) on large-scale datasets. Results show comparable or improved performance for BLS-variants across diverse vision-language and scene text recognition tasks. (a) ToCa dataset (zero-shot captioning, 3M samples). (b) MJ+ST dataset (scene text recognition, 15M samples). (c) SS1M dataset (cross-domain captioning, 3M samples). Pruned % indicates data reduction.
Method
CIFAR10
CIFAR100
30%
50%
70%
30%
50%
70%
ResNet18
95.6
78.2
Random
94.6 ↓1.0
93.3 ↓2.3
90.2 ↓5.4
73.8 ↓4.4
72.1 ↓6.1
69.7 ↓8.5
GraNd-4 [ 34 ]
95.3 ↓0.3
94.6 ↓1.0
91.2 ↓4.4
74.6 ↓3.6
71.4 ↓6.8
68.8 ↓9.4
EL2N-20 [ 45 ]
95.3 ↓0.3
95.1 ↓0.5
91.9 ↓3.7
77.2 ↓1.0
72.1 ↓6.1
-
DP [ 50 ]
94.9 ↓0.7
93.8 ↓1.8
90.8 ↓4.8
77.2 ↓1.0
73.1 ↓5.1
-
Table 2: Comparison of state-of-the-art methods on CIFAR classification (ResNet18, Accuracy %) at different pruning rates. BLS effectively proxies per-sample loss methods to achieve comparable accuracy to original methods under the same pruning rate. † : adjusted epochs in original paper. ‡ : same epochs as other methods. : unattainable ratio. Random*: dynamic random. Performance relative to Full training is indicated ( ↓ : drop, ↑ : gain).
Method
ImageNet-1K
CIFAR100
CNN
Transformer
Mamba
R18
R50
EfficientNet
ViT
Swin
Vim
R18
R50
Full
69.5
78.6
76.1
73.3
80.0
75.7
78.2
80.6
BLS-InfoBatch
69.4 / 32.8
78.2 / 31.5
75.7 / 32.8
73.2 / 26.2
80.0 / 30.8
75.6 / 22.9
78.3 / 33.9
80.5 / 38.6
BLS-SeTa
69.5 / 31.3
78.4 / 32.3
76.0 / 31.1
73.3 / 25.2
80.0 / 44.5
75.6 / 29.4
78.4 / 40.1
80.7 / 40.7
Table 3: BLS demonstrates strong cross-architecture generalization on ImageNet-1K and CIFAR100 with CNNs, Transformers, and Mambas. Format: Accuracy / Pruned %.
Method
Pruned %
NoCaps Val (CIDEr)
COCO
In
Near
Out
Overall
B@4
M
C
S
Full
-
58.4
63.1
65.3
65.2
27.1
24.6
91.5
18.0
BLS-InfoBatch
20.9
58.8
63.1
65.8
65.3
27.1
24.6
91.9
17.9
BLS-SeTa
28.1
58.9
63.1
65.6
65.3
27.2
24.7
92.0
18.0
Table 4: Consolidated results for various methods on different datasets and tasks. (a) ViECap on COCO dataset: Image captioning performance with 556K samples. (b) ViECap on MSR-VTT dataset: Video captioning performance with 180K samples. (c) Ada-MVS on WHU-MVS dataset: Multi-view stereo performance with 28K image-depth map samples.
Method
VAE
DDPM
DDPM-CFG
Pruned %
FID
Pruned %
FID
Pruned %
FID
Full
-
35.34
-
16.38
-
14.89
BLS-InfoBatch
28.9
35.55
28.7
17.01
22.0
14.99
BLS-SeTa
34.0
35.34
30.8
16.35
22.3
14.72
Table 5: Image generation with different architectures (VAE on MNIST, DDPM on CIFAR10, DDPM with Classifier Guidance (CFG) on CIFAR10). FID: Frechet Inception Distance.
Method
Image
Text
Audio
Pruned %
Acc
Pruned %
Acc
Pruned %
Acc
Full
-
61.9
-
53.7
-
64.5
BLS-InfoBatch
31.3
61.9
38.1
54.4
25.0
64.5
BLS-SeTa
47.4
61.9
49.4
54.7
28.7
64.6
Table 6: Semi-supervised learning including image classification (FixMatch on CIFAR100), text sentiment classification (FlexMatch on Yelp Review) and audio classification (Dash on ESC-50).
Method
Image Classification
Object Detection
Instance Segmentation
Pruned %
Acc@1
Acc@5
Pruned %
mAP .5
mAP .5:.95
Pruned %
mAP .5
mAP .5:.95
YOLOv5n
-
58.0
84.6
-
38.2
22.1
-
29.5
16.3
BLS-InfoBatch
20.4
57.6
84.0
21.6
38.5
22.2
29.5
31.0
17.2
BLS-SeTa
35.4
58.0
84.6
25.2
38.3
22.1
36.1
31.7
17.6
Table 7: Enhancing computational efficiency of a unified YOLOv5 framework for image classification on CIFAR100, alongside object detection and instance segmentation on COCO, through BLS.
Figure 2: Empirical validation of frequency separation. Top: Average PSD for scaled signal ( Mean Si ) and batch noise ( Mean Ni ). Bottom: Time series for a representative sample. Si magnitude is much smaller (see inset).
Method
R18
R50
Acc
Time
P %
Acc
Time
P %
Full
78.2
2.46h
-
80.6
4.10h
-
InfoBatch
78.2
1.63h
33.8
80.6
2.74h
33.0
+ w/o EMA BLS
77.9
1.65h
32.8
79.9
2.75h
32.8
+ BLS
78.3
1.63h
33.9
80.6
2.74h
33.1
SeTa
78.3
1.53h
40.0
80.7
2.53h
39.8
Table 8: Ablation study of BLS components on CIFAR100 (ResNet18/50). "P %" denotes Pruning Percentage. "Time" includes pruning cost and training time. "+ BLS" refers to the full BLS integrated method. "+ w/o EMA BLS" uses only the last batch loss for scoring active samples.
Figure 3: Effect of EMA decay factor α . Accuracy and Pruning Ratio are shown for ResNet18 and ResNet50.
Figure 4: Workflow Comparison: BLS Black-Box Simplicity vs. Per-Sample Loss Complexity.
Method
Overhead
R18 P/B 734.1s
R50 P/B 2122.4s
InfoBatch
0.236s
0.03%
0.01%
BLS-InfoBatch
0.253s
0.03%
0.01%
SeTa
10.001s
1.4%
0.5%
BLS-SeTa
10.021s
1.4%
0.5%
Table 9: Computational overhead of BLS with InfoBatch and SeTa (1M samples, NVIDIA RTX 3090 GPU).
Faculty of Engineering, North-West University, South Africa · Centre for Artificial Intelligence Research (CAIR), South Africa · National Institute for Theoretical and Computational Sciences (NITheCS), South Africa