Pioneering 4-Bit FP Quantization for Diffusion Models: Mixup-Sign Quantization and Timestep-Aware Fine-Tuning

• URL: http://arxiv.org/abs/2505.21591v1
• Date: Tue, 27 May 2025 13:40:47 GMT
• Title: Pioneering 4-Bit FP Quantization for Diffusion Models: Mixup-Sign Quantization and Timestep-Aware Fine-Tuning
• Authors: Maosen Zhao, Pengtao Chen, Chong Yu, Yan Wen, Xudong Tan, Tao Chen,
• Abstract summary: Model quantization reduces the bit-width of weights and activations, improving memory efficiency and inference speed.<n>Existing methods, primarily based on integer quantization and post-training quantization fine-tuning, struggle with inconsistent performance.<n>We propose a mixup-sign floating-point quantization framework, first introducing unsigned FP quantization in model quantization, along with timestep-aware LoRA and denoising-factor loss alignment.
• Score: 14.145862114439831
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Model quantization reduces the bit-width of weights and activations, improving memory efficiency and inference speed in diffusion models. However, achieving 4-bit quantization remains challenging. Existing methods, primarily based on integer quantization and post-training quantization fine-tuning, struggle with inconsistent performance. Inspired by the success of floating-point (FP) quantization in large language models, we explore low-bit FP quantization for diffusion models and identify key challenges: the failure of signed FP quantization to handle asymmetric activation distributions, the insufficient consideration of temporal complexity in the denoising process during fine-tuning, and the misalignment between fine-tuning loss and quantization error. To address these challenges, we propose the mixup-sign floating-point quantization (MSFP) framework, first introducing unsigned FP quantization in model quantization, along with timestep-aware LoRA (TALoRA) and denoising-factor loss alignment (DFA), which ensure precise and stable fine-tuning. Extensive experiments show that we are the first to achieve superior performance in 4-bit FP quantization for diffusion models, outperforming existing PTQ fine-tuning methods in 4-bit INT quantization.

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