Papers › Soft Truncation: A Universal Training Technique of Score-based Diffusion Model for...

Soft Truncation: A Universal Training Technique of Score-based Diffusion Model for High Precision Score Estimation

10 Jun 2021arXiv:2106.05527archive 2025-07-28

Dongjun Kim, Seungjae Shin, Kyungwoo Song, Wanmo Kang, Il-Chul Moon

Recent advances in diffusion models bring state-of-the-art performance on image generation tasks. However, empirical results from previous research in diffusion models imply an inverse correlation between density estimation and sample generation performances. This paper investigates with sufficient empirical evidence that such inverse correlation happens because density estimation is significantly contributed by small diffusion time, whereas sample generation mainly depends on large diffusion time. However, training a score network well across the entire diffusion time is demanding because the loss scale is significantly imbalanced at each diffusion time. For successful training, therefore, we introduce Soft Truncation, a universally applicable training technique for diffusion models, that softens the fixed and static truncation hyperparameter into a random variable. In experiments, Soft Truncation achieves state-of-the-art performance on CIFAR-10, CelebA, CelebA-HQ 256x256, and STL-10 datasets.

PaperPDFConference PDFCodeCode Syntology ran

In Syntology Open this paper in Syntology's Atlas, the map of the papers in Syntology's graph and their citations.

For agents, Syntology's MCP tool lists every function and class Syntology harvested from this paper and whether it ran (how to connect): get_harvested_code_for_paper(arxiv_id="2106.05527")

Code

Syntology Ran 4 of 12 code samples harvested from 1 repository linked to this paper; 8 have no recorded run. Of those that ran: 2 ran · our draft was wrong; 2 ran with no contract checked.

By repository: official repository: 12 samples from 1 repository, 4 ran. The run record, sample by sample. “Ran” means executed on a synthesized input, not that the code is correct or reproduces the paper.

Kim-Dongjun/Soft-Truncation officialmentioned in papermentioned on GitHubpytorchApache-2.0 report

Repository list and official/mentioned flags are the archive's, frozen 2025-07-28. Reachability, where shown, is from one Syntology probe window (2026-09-16 to 2026-09-18); repositories not probed show nothing. GitHub stars are not tracked.

Code Syntology ran Syntology

12 samples harvested; 4 ran; 0 honoured the contract we drafted; 8 have no recorded run. Read from Syntology's graph 2026-09-24; that is when this build read the record, not when the samples ran.

2ran · our draft was wrong
2ran
8unverified

Licence: 0 of the 12 samples are pointer only, meaning Syntology does not serve that copy's text. This page shows no code text for any sample; each one links to its file in the repository.

Harvested from Kim-Dongjun/Soft-Truncation. “Ran” means the sample executed on a synthesized input. It does not mean the output is correct, and nothing here reproduces the paper's results. “Honoured” and “violated” refer to a contract Syntology drafted from the code itself; “our draft was wrong” and “fixture could not drive it” are failures of Syntology's instrument, not of the code.

Each sample ends with its code_sha256, Syntology's identity for that exact code. An agent fetches the stored sample with Syntology's MCP tool get_code(code_sha256="…") (how to connect); click an identity to copy that call.

Repository labels, per sample. official repository: The archive marks this repository official for the paper. named in the paper: The archive records that the paper mentions this repository; it is not marked official. community (archive-listed): In the archive's code links for this paper, not marked official and not recorded as mentioned in the paper. found in paper text by Syntology: Syntology found this repository in the paper's own text; whether it is the authors' implementation is not asserted. community: Not in the archive's code links for this paper; a community repository Syntology harvested. Samples from a repository marked official are listed first. Licence labels name the repository's licence as recorded at harvest. “Pointer only” means Syntology does not serve that copy's text, for one of four reasons: no licence file was found; the licence was not identified; the licence is recorded as permissive but that copy's record is not marked cleared; or the licence is outside the permissive list Syntology serves text under (MIT, Apache-2.0, BSD and similar). Some licences outside that list permit redistribution, such as WTFPL, and GPL-3.0 under its conditions; they are simply not on the list. Hover a licence label for the reason. File links open the file on GitHub at the default branch, which may have changed since the harvest.

get_data_inverse_scaler Kim-Dongjun/Soft-Truncation/datasets.py official repository ran · our draft was wrong Apache-2.0 (permissive) · 6c419026e778dee2 · report
get_data_scaler Kim-Dongjun/Soft-Truncation/datasets.py official repository ran · our draft was wrong Apache-2.0 (permissive) · 346d2e6cc8b48a5d · report
optimization_manager Kim-Dongjun/Soft-Truncation/losses.py official repository ran Apache-2.0 (permissive) · 366bb8c7035a2fc8 · report
variance_scaling Kim-Dongjun/Soft-Truncation/models/layers.py official repository ran Apache-2.0 (permissive) · 3ac11bfe0ae80195 · report
classifier_fn_from_tfhub Kim-Dongjun/Soft-Truncation/evaluation.py official repository unverified Apache-2.0 (permissive) · 54a00db9aadf092f · report
crop_resize Kim-Dongjun/Soft-Truncation/datasets.py official repository unverified Apache-2.0 (permissive) · fd14d238ccd5f679 · report
get_act Kim-Dongjun/Soft-Truncation/models/layers.py official repository unverified Apache-2.0 (permissive) · db5f935a1d6b4c2c · report
get_div_fn Kim-Dongjun/Soft-Truncation/likelihood.py official repository unverified Apache-2.0 (permissive) · 0bfcb6b2d940e393 · report
get_normalization Kim-Dongjun/Soft-Truncation/models/normalization.py official repository unverified Apache-2.0 (permissive) · 1b8adb3294e53c6d · report
get_optimizer Kim-Dongjun/Soft-Truncation/losses.py official repository unverified Apache-2.0 (permissive) · f2382220ad5ac587 · report
load_dataset_stats Kim-Dongjun/Soft-Truncation/evaluation.py official repository unverified Apache-2.0 (permissive) · c7b30d41729eeb8e · report
ncsn_conv1x1 Kim-Dongjun/Soft-Truncation/models/layers.py official repository unverified Apache-2.0 (permissive) · 85b2235eb7afaa4f · report

Tasks

Density EstimationImage Generation

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Image Generation CelebA 64x64 DDPM++ (VP, FID) + ST FID 1.9 #9 of 39 Archive leaderboard report
Image Generation CelebA 64x64 DDPM++ (VP, FID) + ST bits/dimension 2.1 #9 of 39 Archive leaderboard report
Image Generation CelebA 64x64 DDPM++ (VP, NLL) + ST FID 2.9 #17 of 39 Archive leaderboard report
Image Generation CelebA 64x64 DDPM++ (VP, NLL) + ST bits/dimension 1.96 #17 of 39 Archive leaderboard report
Image Generation CelebA 64x64 UNCSN++ (RVE) + ST bits/dimension 1.97 #38 of 39 Archive leaderboard report
Image Generation CelebA-HQ 256x256 UNCSN++ (RVE) + ST FID 7.16 #7 of 19 Archive leaderboard report
Image Generation FFHQ 256 x 256 UDM (RVE) + ST FID 5.54 #27 of 51 Archive leaderboard report
Image Generation ImageNet 32x32 DDPM++ (VP, NLL) + ST FID 8.42 #8 of 35 Archive leaderboard report
Image Generation ImageNet 32x32 DDPM++ (VP, NLL) + ST Inception score 11.82 #8 of 35 Archive leaderboard report
Image Generation ImageNet 32x32 DDPM++ (VP, NLL) + ST bpd 3.85 #8 of 35 Archive leaderboard report
Image Generation LSUN Bedroom 256 x 256 UDM (RVE) + ST FID 4.57 #10 of 32 Archive leaderboard report
Image Generation STL-10 UNCSN++ (RVE) + ST FID 7.71 #2 of 31 Archive leaderboard report
Image Generation STL-10 UNCSN++ (RVE) + ST Inception score 13.43 #2 of 31 Archive leaderboard report

Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.

Methods

Diffusion

Report a problem or propose a change · a person checks every report against the paper or source before anything changes; decisions are listed on /corrections