Dual Orthogonal Guidance for Robust Diffusion-based Handwritten Text Generation

Fuente: arXiv
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Main Authors: Nikolaidou, Konstantina, Retsinas, George, Sfikas, Giorgos, Cascianelli, Silvia, Cucchiara, Rita, Liwicki, Marcus
Format: Preprint
Published: 2025
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author Nikolaidou, Konstantina
Retsinas, George
Sfikas, Giorgos
Cascianelli, Silvia
Cucchiara, Rita
Liwicki, Marcus
author_facet Nikolaidou, Konstantina
Retsinas, George
Sfikas, Giorgos
Cascianelli, Silvia
Cucchiara, Rita
Liwicki, Marcus
contents Diffusion-based Handwritten Text Generation (HTG) approaches achieve impressive results on frequent, in-vocabulary words observed at training time and on regular styles. However, they are prone to memorizing training samples and often struggle with style variability and generation clarity. In particular, standard diffusion models tend to produce artifacts or distortions that negatively affect the readability of the generated text, especially when the style is hard to produce. To tackle these issues, we propose a novel sampling guidance strategy, Dual Orthogonal Guidance (DOG), that leverages an orthogonal projection of a negatively perturbed prompt onto the original positive prompt. This approach helps steer the generation away from artifacts while maintaining the intended content, and encourages more diverse, yet plausible, outputs. Unlike standard Classifier-Free Guidance (CFG), which relies on unconditional predictions and produces noise at high guidance scales, DOG introduces a more stable, disentangled direction in the latent space. To control the strength of the guidance across the denoising process, we apply a triangular schedule: weak at the start and end of denoising, when the process is most sensitive, and strongest in the middle steps. Experimental results on the state-of-the-art DiffusionPen and One-DM demonstrate that DOG improves both content clarity and style variability, even for out-of-vocabulary words and challenging writing styles.
format Preprint
id arxiv_https___arxiv_org_abs_2508_17017
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dual Orthogonal Guidance for Robust Diffusion-based Handwritten Text Generation
Nikolaidou, Konstantina
Retsinas, George
Sfikas, Giorgos
Cascianelli, Silvia
Cucchiara, Rita
Liwicki, Marcus
Computer Vision and Pattern Recognition
Diffusion-based Handwritten Text Generation (HTG) approaches achieve impressive results on frequent, in-vocabulary words observed at training time and on regular styles. However, they are prone to memorizing training samples and often struggle with style variability and generation clarity. In particular, standard diffusion models tend to produce artifacts or distortions that negatively affect the readability of the generated text, especially when the style is hard to produce. To tackle these issues, we propose a novel sampling guidance strategy, Dual Orthogonal Guidance (DOG), that leverages an orthogonal projection of a negatively perturbed prompt onto the original positive prompt. This approach helps steer the generation away from artifacts while maintaining the intended content, and encourages more diverse, yet plausible, outputs. Unlike standard Classifier-Free Guidance (CFG), which relies on unconditional predictions and produces noise at high guidance scales, DOG introduces a more stable, disentangled direction in the latent space. To control the strength of the guidance across the denoising process, we apply a triangular schedule: weak at the start and end of denoising, when the process is most sensitive, and strongest in the middle steps. Experimental results on the state-of-the-art DiffusionPen and One-DM demonstrate that DOG improves both content clarity and style variability, even for out-of-vocabulary words and challenging writing styles.
title Dual Orthogonal Guidance for Robust Diffusion-based Handwritten Text Generation
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2508.17017