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CRoSS: Diffusion Model Makes Controllable, Robust and Secure Image Steganography (Supplementary Material)

Neural Information Processing Systems

Below, we will introduce the details of each stage separately. In practical applications of image steganography, it is common to hide a single subject in an image, and this is also a problem that our method excels at solving. We employed two methods to obtain "Prompt1" and "Prompt2": an ChatGPT to generate the modified "Prompt2". The specific process of generating "Prompt2" is shown in Fig. A.1. We present examples from the Stego260 dataset in Fig. A.2, where each example consists of an image We show images from three categories: humans, animals, and general objects.










A Theoretical and Empirical Taxonomy of Imbalance in Binary Classification

Essomba, Rose Yvette Bandolo, Fokoué, Ernest

arXiv.org Machine Learning

Class imbalance significantly degrades classification performance, yet its effects are rarely analyzed from a unified theoretical perspective. We propose a principled framework based on three fundamental scales: the imbalance coefficient $η$, the sample--dimension ratio $κ$, and the intrinsic separability $Δ$. Starting from the Gaussian Bayes classifier, we derive closed-form Bayes errors and show how imbalance shifts the discriminant boundary, yielding a deterioration slope that predicts four regimes: Normal, Mild, Extreme, and Catastrophic. Using a balanced high-dimensional genomic dataset, we vary only $η$ while keeping $κ$ and $Δ$ fixed. Across parametric and non-parametric models, empirical degradation closely follows theoretical predictions: minority Recall collapses once $\log(η)$ exceeds $Δ\sqrtκ$, Precision increases asymmetrically, and F1-score and PR-AUC decline in line with the predicted regimes. These results show that the triplet $(η,κ,Δ)$ provides a model-agnostic, geometrically grounded explanation of imbalance-induced deterioration.