<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Gradient-Penalty GAN Framework for High-Fidelity Fingerprint Synthesis</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Oleksandr Striuk</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yuriy Kondratenko</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Institute of AI Problems under MES and NAS of Ukraine</institution>
          ,
          <addr-line>str. Mala Zhytomyrska, 11, office 5a, Kyiv, 01001</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Petro Mohyla Black Sea National University</institution>
          ,
          <addr-line>68 Desantnykyv St. 10, Mykolaiv, 54000</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>University of Ostrava, Department of Mathematics</institution>
          ,
          <addr-line>Dvořákova 7, Ostrava, 70103</addr-line>
          ,
          <country country="CZ">Czech Republic</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>The rapid advancements in generative adversarial networks (GANs) have significantly impacted digital content synthesis, presenting both opportunities and challenges in multimedia forensics and cybersecurity. We present an Enhanced Adaptive DCGAN (EADC-GAN) for generating high-fidelity synthetic fingerprints, addressing core challenges in training stability and sample diversity. By combining Wasserstein loss with gradient penalty (WGAN-GP), instance normalization in the discriminator, and tailored architectural refinements, our model achieves strong image realism at reduced training cost. Compared to prior DCGANbased methods, EADC-GAN synthesizes more diverse, artifact-free samples in fewer epochs, making it suitable for scalable biometric data generation. This has key implications for secure authentication, privacypreserving biometric datasets, and adversarial robustness in cybersecurity contexts.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Synthetic fingerprints</kwd>
        <kwd>generative adversarial networks</kwd>
        <kwd>WGAN-GP</kwd>
        <kwd>DCGAN</kwd>
        <kwd>instance normalization</kwd>
        <kwd>biometric security</kwd>
        <kwd>adversarial robustness</kwd>
        <kwd>deep learning</kwd>
        <kwd>cybersecurity</kwd>
        <kwd>fingerprint synthesis1</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>In the modern era, artificial intelligence (AI) and information technology (IT) have become deeply
embedded in nearly every aspect of human activity, driving advancements in automation,
decisionmaking, and security. From smart homes to autonomous systems, AI-powered solutions enhance
efficiency and enable novel applications across industries. In particular, AI has revolutionized forensic
investigations and secure access control systems, where accurate and reliable identification methods
are crucial [7, 30, 32].</p>
      <p>Fingerprint-based biometric systems have become a cornerstone of modern security
infrastructures, owing to their robustness and uniqueness in identifying individuals. With
applications ranging from smartphone authentication to large-scale national identity programs, the
demand for high-quality, reliable fingerprint data has soared.</p>
      <p>
        However, the collection of large-scale, diverse, and privacy-preserving fingerprint datasets can be
both resource-intensive and ethically fraught. This challenge has prompted research into synthetic
fingerprint generation methods that can provide abundant, high-fidelity data without exposing
sensitive personal information [
        <xref ref-type="bibr" rid="ref1 ref2">1, 2</xref>
        ].
      </p>
      <p>
        Generative Adversarial Networks (GANs) have emerged as efficient tools for synthetic and realistic
data generation, offering compelling results in various domains including image, video, and audio
synthesis. Despite their success, early GAN models often suffered from training instabilities and mode
collapse, limiting their applicability to more sensitive tasks such as fingerprint synthesis [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
Variations like Deep Convolutional GANs (DCGANs) introduced architectures tailored for image
generation, yet challenges remained, particularly when targeting both high quality and diversity in
the generated outputs [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ].
      </p>
      <p>
        One promising improvement to the GAN framework is the use of gradient penalty techniques,
such as those found in Wasserstein GANs with Gradient Penalty (WGAN-GP), which offer enhanced
training stability. Additionally, normalization layers have a profound impact on the training dynamics
and generation quality of GANs. Adaptive instance normalization (AIN), for example, has shown the
capability to improve style consistency and reduce artifacts in image synthesis tasks [
        <xref ref-type="bibr" rid="ref5 ref6">5, 6</xref>
        ].
      </p>
      <p>Early approaches to fingerprint image synthesis explored traditional models such as DCGAN. In
our previous work, Adaptive Deep Convolutional GAN for Fingerprint Sample Synthesis (ADCGAN),
we demonstrated that a well-tuned DCGAN could generate visually convincing fingerprints [7].
However, the method exhibited two main drawbacks. First, achieving photorealistic fingerprints
demanded a large number of epochs — often exceeding 1,000 — to reach acceptable quality. Second,
despite eventually producing samples with realistic ridge patterns, the model became prone to mode
collapse at higher epoch counts. This collapse led to repetitive samples and diminished the overall
diversity of the generated dataset. The need for extensive training time also poses challenges for
projects with limited computational resources or time-sensitive development cycles [7].</p>
      <p>In this paper, we present a Gradient-Penalty GAN Framework for high-fidelity fingerprint
synthesis, leveraging insights from both WGAN-GP and enhanced normalization strategies [8, 9, 10].
We build upon the insights gained from ADCGAN, refining the architecture and training strategy to
yield higher-quality samples in fewer epochs while minimizing mode collapse.</p>
      <p>By optimizing the instance normalization layers and incorporating gradient penalty, we aim to
address training instability and mode diversity issues that often hinder fingerprint GAN models. Our
experimental evaluations demonstrate that this architecture not only produces more realistic and
varied fingerprint images but also reduces the computational overhead commonly associated with
GAN enhancements.</p>
      <p>Crucially, the synthesized fingerprints can bolster biometric research by providing large-scale
datasets and facilitating the development of advanced, secure authentication systems without
compromising user privacy.</p>
      <p>Despite advances in GAN-based fingerprint synthesis, existing models often struggle with training
instability, mode collapse, and insufficient diversity in generated samples. Additionally, many
methods require extensive computational resources and training time, limiting their practical use in
scalable biometric systems. This work addresses these limitations by proposing a more stable, efficient
GAN framework capable of producing realistic, high-resolution fingerprint images with minimal
redundancy.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related Work</title>
      <sec id="sec-2-1">
        <title>2.1. GAN-Based Image Synthesis Approaches</title>
        <p>
          GANs have become a central method for synthesizing diverse image datasets, including biometric
images such as fingerprints. Early efforts often relied on the DCGAN framework, which demonstrated
that transposed convolution layers could capture essential fingerprint patterns. However, these
classical DCGANs typically require extensive training, and they remain susceptible to mode collapse
— where the generator converges to limited variations of the same fingerprint. Recent approaches
have aimed to mitigate these issues by integrating more advanced loss functions and architectural
refinements, making GAN-based finger-print synthesis both more efficient and more robust in
capturing fine ridge details [
          <xref ref-type="bibr" rid="ref5 ref6">5, 6</xref>
          ].
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Fingerprint Synthesis Techniques</title>
        <p>Early fingerprint generation efforts often employed parametric and procedural models, focusing on
ridge flow simulation and minutiae placement through mathematical functions. Techniques such as
Gabor-based filters, Fourier transforms, and partial differential equations (PDEs) aimed to replicate
key fingerprint structures without relying on large training sets. Although these methods can yield
convincing ridge patterns and minutiae distributions, they sometimes lack the capacity to produce the
extensive variability needed for modern biometric applications.</p>
        <p>In contrast, deep learning–driven approaches like GANs learn distributional properties directly
from real data, offering greater flexibility and diversity in synthesized outputs. Beyond standard
DCGAN-based solutions, advanced architectures — such as StyleGAN and CycleGAN — further refine
texture details, enhance global coherence, and address common pitfalls like mode collapse. Together,
both classical (model-based) and deep learning–based techniques enrich the toolbox for generating
comprehensive, privacy-friendly fingerprint datasets [7, 11, 12].</p>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. Normalization in GANs</title>
        <p>Normalization layers are crucial for stabilizing GAN training, and adaptive instance normalization
offers particular benefits for image synthesis tasks that depend on local texture fidelity. While batch
normalization averages statistics across a mini-batch, instance normalization normalizes each sample
independently, helping preserve distinctive ridges and fine details in synthetic fingerprints. Instance
normalization can reduce style variations within a single batch — an advantage when the primary goal
is to maintain consistent textural cues. As a result, integrating instance normalization, especially in
the discriminator, can sharpen feature detection and further mitigate common GAN pitfalls such as
training instability and overly uniform outputs [13, 14].</p>
      </sec>
      <sec id="sec-2-4">
        <title>2.4. Gradient Penalty Methods (WGAN-GP and Beyond)</title>
        <p>The Wasserstein GAN (WGAN) framework addresses two key shortcomings in conventional GANs:
vanishing gradients and unstable training. By replacing the standard generator-discriminator loss
with the Wasserstein distance, WGAN provides a meaningful gradient signal that promotes better
convergence. To further stabilize training, WGAN with Gradient Penalty (WGAN-GP) incorporates a
gradient penalty term that enforces Lipschitz continuity without resorting to weight clipping. This
penalty term substantially reduces mode collapse and improves sample diversity. In the context of
fingerprint synthesis, WGAN-GP’s training stability helps produce more varied and realistic
fingerprint ridges over fewer epochs [8, 9].</p>
        <p>
          Unlike classical DCGAN-based approaches that rely heavily on batch normalization and often
exhibit mode collapse, our method introduces instance normalization in the discriminator and
leverages WGAN-GP for improved gradient flow. This combination enhances both training stability
and output diversity. While models like StyleGAN and CycleGAN achieve high visual fidelity, they
often require complex tuning and are not specifically tailored to biometric features [
          <xref ref-type="bibr" rid="ref5">5, 15, 17</xref>
          ]. In
contrast, our architecture is optimized for fingerprint synthesis, balancing computational efficiency
with domain-specific texture preservation.
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Proposed Methodology</title>
      <sec id="sec-3-1">
        <title>3.1. Normalized DCGAN Architecture</title>
        <p>The proposed model builds upon the standard DCGAN framework — originally designed to generate
high-quality images through transposed convolutions in the generator and strided convolutions in the
discriminator.</p>
        <p>However, instead of using batch normalization throughout, we use instance normalization in the
discriminator to improve training stability and capture finer textures critical for biometric features.</p>
        <p>DCGAN was chosen as the foundation due to its proven effectiveness in structured image
generation, including biometric textures. Its simplicity and modularity make it highly adaptable for
fingerprint synthesis. By replacing batch normalization with instance normalization and integrating
WGAN-GP, we retain DCGAN’s strengths while resolving its typical weaknesses — namely, training
instability and low sample diversity. This adapted framework strikes a practical balance between
architectural simplicity, computational efficiency, and output quality.</p>
        <p>Generator follows a classic DCGAN-like upsampling pipeline, which transforms a latent noise
vector into a full-resolution fingerprint image through stacked transposed convolutional layers, batch
normalization, and ReLU activations.</p>
        <p>Discriminator mirrors the generator’s structure in a downsampling fashion but replaces batch
normalization with instance normalization layers. LeakyReLU activations are retained to preserve
gradient flow. Instead of normalizing over the entire batch, instance normalization (IN) scales and
shifts each sample independently. Fingerprint images demand precise ridge patterns. IN helps retain
such fine-grained textures without inadvertently averaging them out across a mini-batch [13, 15, 16,
17].</p>
        <p>By combining instance normalization with the WGAN-GP training strategy, the model is less
prone to collapsing to repetitive samples. Empirical observations show that instance normalization
can better capture local variations, which are paramount for realistic fingerprint synthesis. In the
following sections, we detail how gradient penalty is integrated to further stabilize training and
discuss the specific loss functions and optimization protocol that tie into the model architecture.</p>
        <sec id="sec-3-1-1">
          <title>Convolution (Output)</title>
        </sec>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Integration of Gradient Penalty</title>
        <p>To stabilize training and mitigate mode collapse, we adopt the WGAN-GP framework, which enforces
Lipschitz continuity through a gradient penalty on the discriminator's output. Unlike weight clipping
used in early WGANs, this penalty regularizes gradient norms for interpolated real and fake samples,
improving convergence without harming model capacity [8, 9].</p>
        <p>In each training iteration, the algorithm samples a random scalar α from a uniform distribution
U ( 0,1 ). A point ^x is then created by interpolating between a real sample xreal and a generated sample
xfake. The discriminator’s gradient is computed on ^x.</p>
        <p>Let’s formulate the loss. If D denotes the discriminator, its Wasserstein distance–based objective
incorporates an added penalty term:</p>
        <p>λgp⋅ (‖∇ D ( ^x )‖2−1 )2
where λgp is a hyperparameter dictating the penalty’s strength.</p>
        <p>By penalizing large deviations of ‖∇ D ( ^x )‖2 from 1, the discriminator remains closer to a valid
1Lipschitz function, leading to more reliable gradients for the generator [8, 9].</p>
        <p>The gradient penalty term mitigates abrupt updates in the discriminator that commonly cause
training to diverge. By preserving a stable gradient flow, the generator avoids collapsing to a narrow
subset of fingerprints. Because the discriminator’s updates remain well-conditioned, the model can
converge to realistic fingerprint patterns in fewer epochs compared to weight-clipped or standard
DCGAN setups [8, 9].</p>
        <p>In the next sections, we detail how this WGAN-GP loss formulation is combined with instance
normalization, specialized generator and discriminator architectures, and the overall training
workflow to produce high-quality, diverse fingerprint images.</p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Loss Functions and Optimization Strategy</title>
        <p>The training process adopts the WGAN-GP framework, which replaces the traditional adversarial loss
with an objective based on the Wasserstein distance. Below are the key components [8, 9].</p>
        <p>Discriminator (Critic) Loss:
(1)
(3)
LD= Ex∼ pdata [ D ( x )]− Ez∼ pz [ D (G ( z ))]+ λgp E^x [(‖∇ D ( ^x )‖2−1)2]
(2)
where LD is the discriminator loss, E is expectation, D is the discriminator, G is the generator,
x are real samples, z are noise vectors from a prior distribution (e.g., N ( 0,1 )), ^x is an interpolated
sample between real and generated data, and λgp scales the gradient penalty.</p>
        <p>Generator Loss:</p>
        <p>LG=− Ez∼ pz [ D (G ( z ))]
where LG is the generator loss.</p>
        <p>Adam is employed for both generator and discriminator, with learning rate ≈ 2 × 10−4, β1 = 0.5,
and β2 = 0.999. These parameters promote stable convergence in convolutional architectures,
particularly with the gradient penalty term.</p>
        <p>A common strategy in WGAN-based setups is to update the discriminator more often than the
generator (e.g., 5:1 ratio), ensuring the critic remains sufficiently accurate to guide generator updates.</p>
        <p>Gradient penalty enforces a smooth, 1-Lipschitz constraint without resorting to weight clipping.
Instance normalization in the discriminator helps preserve detailed ridge features in fingerprints and
ensures stable gradient flow [8, 9].</p>
        <p>By combining WGAN-GP loss functions, careful hyperparameter tuning, and selective update
frequencies, the model converges faster and produces higher-fidelity fingerprint images than standard
DCGAN-based methods.</p>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Algorithmic Workflow</title>
        <p>
          The training pipeline, informed by the enhanced EADC-GAN implementation, proceeds through a
structured sequence of steps designed to systematically refine both the generator and discriminator
networks. Initially, the model configurations and hyperparameters are defined, including the number
of epochs, batch size, latent dimension, learning rate, and the gradient penalty coefficient. Fingerprint
images, resized to 128×128 pixels and normalized to the [
          <xref ref-type="bibr" rid="ref1">−1,1</xref>
          ], are loaded through a shuffling
mechanism that ensures an unbiased sampling process across mini-batches.
        </p>
        <p>Once the data is loaded, the generator and discriminator networks are initialized. The generator
uses DCGAN-like architecture to transform a latent vector z∈ R100 into a 128×128 image. It applies
transposed convolutions, batch normalization, ReLU activations, and ends with a Tanh layer. The
discriminator mirrors a downsampling approach, incorporating instance normalization and
LeakyReLU activations. To enable stable convergence, both networks initialize their learnable
parameters with random values drawn from a normal distribution centered at zero with a standard
deviation of 0.02.</p>
        <p>The core training cycle repeats for each epoch and processes one mini-batch of fingerprint data at
a time. In each iteration, the discriminator is first updated by sampling real fingerprint imagesxreal
from the dataset and generating fake images xfake=G ( z ) from randomly sampled noise vectors z. The
Wasserstein distance is then computed as the difference in discriminator outputs on real and fake
samples, and the gradient penalty term is imposed through an interpolation strategy that regularizes
the norm of the discriminator’s gradients. These gradient-based objectives are combined, and the
discriminator parameters are updated accordingly via backpropagation with an Adam optimizer,
using momentum parameters β =(0.5 , 0.999).</p>
        <p>After the discriminator update, the generator is refined at a reduced frequency (for instance, every
five discriminator iterations) to maintain a reliable critic. In this phase, fresh noise vectors are drawn
from the latent distribution, passed through the generator, and evaluated by the discriminator. The
generator’s loss function aims to maximize the discriminator’s output on these synthesized images,
effectively minimizing the negative Wasserstein distance. By backpropagating this signal, the
generator weights are adjusted to create more plausible and diverse fingerprint images in subsequent
iterations.</p>
        <p>Throughout training, the system periodically saves both model checkpoints and synthetic images
generated from a fixed set of noise vectors. These outputs allow for consistent evaluation of the
generator’s progression over time and facilitate direct comparison across epochs. Upon completion,
the final weights of the generator and discriminator are stored for downstream usage, such as bulk
synthetic fingerprint generation or further fine-tuning. By blending frequent discriminator updates, a
gradient penalty mechanism, and controlled generator refinement, the workflow produces
highfidelity and structurally diverse fingerprint images within a stable and computationally efficient
training regime.</p>
        <p>Below is a comparison table that presents architectural differences between the models — our
previous ADC-GAN and EADC-GAN [7].</p>
      </sec>
      <sec id="sec-3-5">
        <title>3.1. Theoretical Contribution and Novelty</title>
        <p>This work presents a novel synthesis of two stabilizing strategies — gradient penalty from WGAN-GP
and instance normalization in the discriminator — to improve the fidelity and diversity of fingerprint
generation. While both techniques have been explored separately in GAN literature, their combined
use and fine-tuning in a domain-specific architecture for fingerprint synthesis is new, and, to our
knowledge, no prior fingerprint-synthesis study combines IN and WGAN-GP. Our results
demonstrate that this hybrid strategy enables faster convergence, reduces mode collapse, and
preserves fine-grained biometric details more effectively than conventional batch-normalized
DCGANs or standard WGAN-GP models.</p>
        <sec id="sec-3-5-1">
          <title>Generator</title>
        </sec>
        <sec id="sec-3-5-2">
          <title>Architecture</title>
        </sec>
        <sec id="sec-3-5-3">
          <title>Discriminator</title>
        </sec>
        <sec id="sec-3-5-4">
          <title>Architecture</title>
        </sec>
        <sec id="sec-3-5-5">
          <title>Unique Features</title>
        </sec>
        <sec id="sec-3-5-6">
          <title>Adam optimizer with separate learning rates: Generator lr = 0.0001, Discriminator lr = 0.0002; β₁ = 0.5, β₂ = 0.999.</title>
        </sec>
        <sec id="sec-3-5-7">
          <title>A sequential model that uses a</title>
          <p>series of ConvTranspose2d layers
to upsample the latent vector
directly into a 64×64 image; final
activation is Tanh.</p>
        </sec>
        <sec id="sec-3-5-8">
          <title>Starts with a fully connected (fc)</title>
          <p>layer that projects the latent
vector into a feature map
(reshaped to an 8×8 spatial size)
followed by several</p>
        </sec>
        <sec id="sec-3-5-9">
          <title>ConvTranspose2d layers to</title>
          <p>upscale to 128×128; final
activation is Tanh.</p>
          <p>A sequential network of Conv2d A sequential network of Conv2d
layers with BatchNorm (except the layers using instance
first layer) and LeakyReLU normalization and LeakyReLU
activations; ends with a Sigmoid to activations; does not use a
output a probability score. Sigmoid activation in the final
layer – it outputs a single scalar
value for WGAN-based loss
calculation.</p>
          <p>Implements a modified DCGAN Incorporates instance
architecture with BCE loss, normalization in the discriminator,
adaptive learning rates, robust modified batch normalization, and
weight initialization, and batch a gradient penalty term in the loss
normalization techniques. (WGAN-GP), improving training
stability, computational
effectiveness, and image quality in
higher resolution settings.</p>
          <p>Furthermore, we extend the practical utility of WGAN-GP by applying it to a biometric domain
with strict texture preservation needs, showing its scalability to higher resolutions (128×128) with
reduced training costs. This framework can serve as a foundational baseline for synthetic biometric
data generation, adversarial robustness studies, and privacy-focused authentication system design.</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Experimental Setup</title>
      <sec id="sec-4-1">
        <title>4.1. Datasets and Preprocessing</title>
        <p>The experimental analysis utilizes a curated subset of fingerprint images drawn from a publicly
available biometric dataset — SOCOFing [18]. The data includes grayscale samples, exhibit variability
in ridge patterns, and contrast.</p>
        <p>
          To achieve consistency across samples, each fingerprint image is resized to a fixed spatial
dimension of 128×128 pixels and normalized to the range [
          <xref ref-type="bibr" rid="ref1">−1,1</xref>
          ]. This normalization aligns with the
output of the generator’s Tanh activation, facilitating stable training dynamics and seamless
comparisons across different batches.
        </p>
        <p>The grayscale format (single-channel) not only reduces computational overhead but also
highlights finer ridge and valley structures, which are central to realistic fingerprint generation.
Throughout the preprocessing pipeline, data is split into training and validation subsets, although the
adversarial framework primarily relies on the training partition for iterative updates.</p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. Evaluation Metrics</title>
        <p>The model monitors training progress primarily through discriminator and generator loss values, as
well as periodic visual inspection of generated samples. By regularly printing the Wasserstein-based
objective for both networks, we were able to quickly identify training instabilities. Meanwhile, saving
a fixed batch of synthetic fingerprint images over multiple epochs provides a direct, qualitative
perspective on improvements in ridge fidelity and overall realism.</p>
        <p>Relying on losses and sample outputs offers a lightweight yet effective evaluation strategy. In
highdetail domains like fingerprint synthesis, real-time visual checks can be more intuitive than abstract
numeric scores, enabling domain experts to spot subtle artifacts or textural inconsistencies. This
approach also simplifies model development by reducing the computational overhead of advanced
metrics (e.g., Fréchet Inception Distance), which often require large external classifiers or additional
memory usage.</p>
        <p>If a more robust, quantitative benchmark is desired, metrics like FID or Inception Score can be
incorporated at a later stage to complement the qualitative insights gained from losses and sample
images.</p>
      </sec>
      <sec id="sec-4-3">
        <title>4.3. Implementation Details and Hyperparameter Settings</title>
        <p>Model training is conducted using PyTorch, leveraging GPU acceleration. Both generator and
discriminator networks are initialized with weights drawn from a normal distribution ( μ=0,
σ =0.02), consistent with DCGAN best practices. The Adam optimizer [19] is applied to each
network’s parameters.</p>
        <p>The discriminator (equipped with instance normalization) is updated for every mini-batch, while
the generator receives updates at a slightly reduced frequency (e.g., once every five discriminator
steps), preserving a balanced training signal.</p>
        <p>The gradient penalty coefficient λgp is set to 10, based on prior WGAN-GP literature that suggests
it effectively constrains the gradient norm [8, 9].</p>
        <p>Training proceeds for up to 200 epochs — substantially fewer than the 1,000+ epochs sometimes
required by earlier DCGAN-based methods — owing to the stabilizing influence of gradient penalty
and the enhanced texture preservation afforded by instance normalization.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Results and Analysis</title>
      <sec id="sec-5-1">
        <title>5.1. Qualitative Assessment</title>
        <p>Generated fingerprint samples display high-fidelity ridge patterns and minimal visual artifacts,
particularly in mid-to-late training epochs. Qualitatively, synthetic images exhibit distinct papillary
lines, consistent contrast levels, and plausible global orientations that resemble real biometric data. By
periodically saving and reviewing the generator’s outputs, we could observe a steady progression
from coarse, noisy impressions to well-defined ridge structures.</p>
        <p>Notably, improvements occur with only 170—200 epochs compared to 1200 epochs of the earlier
DCGAN-based model, reflecting the stabilizing influence of the gradient penalty and instance
normalization.</p>
      </sec>
      <sec id="sec-5-2">
        <title>5.2. Normalization and Penalty Variants</title>
        <p>Ablation experiments indicate that substituting batch normalization with instance normalization in
the discriminator enhances texture preservation and mitigates mode collapse. When batch
normalization is reintroduced, training exhibits higher variance in discriminator loss and a slight
decline in sample diversity. Similarly, reducing or removing the gradient penalty coefficient ( λgp)
increases the likelihood of training instabilities and partially reintroduces repetitive patterns in
generated outputs.</p>
        <p>These findings confirm that both instance normalization and a carefully tuned gradient penalty are
key contributors to generating varied fingerprints.</p>
      </sec>
      <sec id="sec-5-3">
        <title>5.3. Computational Efficiency and Scalability</title>
        <p>Despite incorporating gradient penalty and additional normalization layers, the model proves
computationally efficient relative to extended training regimes of-ten required by baseline DCGANs.</p>
        <p>In practical experiments, fewer total epochs are needed to attain comparable — or superior — visual
fidelity. Moreover, the approach scales well on standard GPU hardware, supporting batch sizes large
enough to accelerate convergence. This efficiency stems from the stable gradient updates afforded by
WGAN-GP, which reduce the need for extensive hyperparameter searches and lessen the risk of early
divergence, making the framework suitable for larger datasets or more complex biometric tasks.</p>
      </sec>
      <sec id="sec-5-4">
        <title>5.4. Evaluation of Results</title>
        <p>The training dynamics of the model exhibit an initial phase of instability, particularly in the
discriminator’s loss, which starts at an excessively high value in the first epoch. This behavior
suggests that the gradient penalty term may have been dominating due to scaling. However, within
the first few epochs, the discriminator loss rapidly decreases and stabilizes around -0.5 to -0.8,
indicating that the discriminator quickly adapts to distinguishing real from generated samples.
Simultaneously, the generator loss begins at a low value and progressively increases, demonstrating
an initial struggle to generate realistic samples. By epochs 10–20, the adversarial balance improves, as
evidenced by the increasing generator loss and stabilized discriminator loss, suggesting that the
generator is effectively learning to produce more convincing outputs.</p>
        <p>Below are samples of artificial fingerprints generated by EADC-GAN after 170 and 200 epochs,
respectively.</p>
        <p>For comparison, the results after 1,000 to 1,300 training epochs are presented below. The samples
clearly demonstrate mode collapse, along with low-resolution quality.</p>
        <p>Beyond epoch 40, the training stabilizes further, with the generator loss continuing to rise and
reaching values around 4.0 by epoch 100. This steady increase indicates that the generator is
persistently improving its ability to generate high-quality images, while the discriminator maintains a
controlled dominance. The gradient penalty (λ=10) appears to regulate training effectively,
preventing extreme discriminator outputs and ensuring stable adversarial interactions. However, the
increasing generator loss may warrant further investigation to rule out potential training
inefficiencies or diminishing discriminator feedback. Overall, the observed loss trends suggest that the
model is learning effectively, but parameter tuning — especially for the gradient penalty coefficient —
could further optimize convergence dynamics.</p>
        <p>The model was trained using the Kaggle cloud environment with an NVIDIA Tesla
P100PCIE-16GB GPU, running CUDA 12.6 and driver version 560.35.03.</p>
      </sec>
    </sec>
    <sec id="sec-6">
      <title>6. Cybersecurity and Biometric Implications</title>
      <sec id="sec-6-1">
        <title>6.1. Integration in Biometric Authentication Systems</title>
        <p>The capacity to generate high-fidelity synthetic fingerprints raises important considerations for both
security researchers and practitioners. On one hand, it offers a privacy-preserving means of
advancing biometric systems by enabling robust testing and algorithmic development without
exposing sensitive personal information. On the other hand, it introduces potential vulnerabilities
that adversaries could exploit if protective measures are not effectively enforced [20, 21].</p>
        <p>By accurately capturing the visual and structural attributes of real fingerprints, the proposed
generative model can supply large synthetic datasets for training and validation in biometric
authentication systems. These “privacy-friendly” samples minimize the legal and ethical constraints
associated with collecting user data at scale, while still reflecting realistic ridge patterns crucial for
ensuring system reliability.</p>
        <p>In practice, developers can use this influx of synthetic samples to enhance feature extraction
methods, improve fingerprint-matching algorithms, and conduct comprehensive stress testing against
external conditions such as image quality variations or sensor discrepancies. The resulting
improvements in accuracy and robustness can bolster consumer confidence in biometric
authentication solutions across various sectors, including mobile devices, secure facility access, and
eGovernment initiatives [22].</p>
      </sec>
      <sec id="sec-6-2">
        <title>6.2. Adversarial Vulnerabilities and Mitigation</title>
        <p>While the generation of realistic fingerprint images aids legitimate research, it concurrently
highlights potential avenues for adversarial attacks. Malicious actors could use convincing synthetic
fingerprints to probe or bypass fingerprint recognition systems. This possibility underscores the need
to develop spoof detection or presentation attack detection mechanisms capable of distinguishing
artificially generated ridges from authentic biometric inputs.</p>
        <p>Countermeasures may include specialized classifiers trained on adversarially generated images,
advanced liveness detection technologies, or multi-factor authentication procedures that combine
fingerprint data with other identifiers. By integrating these preventative strategies, security experts
can leverage the benefits of synthetic biometric training data without compromising user safety and
privacy [23, 24, 25, 26, 27, 28, 29].</p>
      </sec>
    </sec>
    <sec id="sec-7">
      <title>7. Conclusion and Future Directions</title>
      <p>High-fidelity synthetic fingerprints offer both opportunities for biometric advancement and risks of
misuse. They enable privacy-preserving testing and development but also raise security concerns if
safeguards are lacking.</p>
      <p>While the proposed EADC-GAN framework outperforms traditional DCGANs in terms of
convergence speed and visual fidelity, it still requires substantial GPU resources for optimal
performance. Moreover, the current evaluation relies primarily on qualitative assessments, lacking
explicit quantitative metrics such as the Fréchet Inception Distance or specialized fingerprint
matching scores. Additionally, the model’s ability to generate ultra-high-resolution fingerprints (e.g.,
&gt;256×256 pixels) remains to be fully explored — a critical requirement for certain forensic or
highsecurity applications.</p>
      <p>Future work may focus on scaling the architecture to support higher resolutions and embedding
domain-specific fingerprint features tailored for forensic or advanced biometric scenarios [30–32].
Exploring alternative normalization strategies, such as hybrid or adaptive instance normalization
[3335], could further enhance ridge style consistency. Incorporating quantitative evaluation metrics
specific to fingerprint quality — potentially benchmarked against live-capture datasets — would also
strengthen the model’s practical utility.</p>
      <p>Finally, integrating spoof-detection modules directly into the training loop may help preemptively
mitigate adversarial vulnerabilities [36-39]. By pursuing these directions, the proposed framework
can evolve into a robust and versatile tool for both secure biometric authentication [40, 41] and
adversarial AI research [42, 43].</p>
    </sec>
    <sec id="sec-8">
      <title>Declaration on Generative AI</title>
      <p>During the preparation of this work, the authors used Grammarly in order to: Grammar and spelling
check. After using this tool, the authors reviewed and edited the content as needed and take full
responsibility for the publication’s content.
[7] O. Striuk and Y. Kondratenko, “Adaptive Deep Convolutional GAN for Fingerprint Sample
Synthesis,” in Proceedings of 2021 IEEE 4th International Conference on Advanced Information and
Communication Technologies (AICT), 2021, pp. 193—196.
[8] M. Arjovsky, S. Chintala, and L. Bottou, “Wasserstein Generative Adversarial Networks,” in</p>
      <p>Proceedings of the 34th International Conference on Machine Learning, 2017, pp. 214-223.
[9] I. Gulrajani, F. Ahmed, M. Arjovsky, V. Dumoulin, and A. C. Courville, “Improved Training of</p>
      <p>Wasserstein GANs,” in Advances in Neural Information Processing Systems, 2017, pp. 5767-5777.
[10] X. Wei, B. Gong, Z. Liu, W. Lu, and L. Wang, “Improving the Improved Training of Wasserstein</p>
      <p>GANs: A Consistency Term and Its Dual Effect,” arXiv preprint arXiv:1803.01541, 2018.
[11] S. Yoon, J. Feng, and A. K. Jain, “Latent fingerprint enhancement via robust orientation field
estimation,” IEEE Transactions on Information Forensics and Security, vol. 10, no. 4, pp. 877-887,
2015.
[12] R. V. S. Srikanth, A. N. Kumar, “Synthetic Fingerprint Generation using Generative Adversarial
Network,” 2021 6th International Conference on Inventive Computation Technologies (ICICT),
2021, pp. 962-967.
[13] S. Ioffe and C. Szegedy, “Batch normalization: Accelerating deep network training by reducing
internal covariate shift,” in International conference on machine learning, 2015, pp. 448-456.
[14] O. S. Striuk, Y. P. Kondratenko, “Optimization Strategy for Generative Adversarial Networks</p>
      <p>Design,” International Journal of Computing, vol. 22, issue 3, pp. 292-301, 2023.
[15] X. Huang and S. Belongie, “Arbitrary Style Transfer in Real-Time with Adaptive Instance
Normalization,” 2017 IEEE International Conference on Computer Vision (ICCV), Venice, Italy,
2017, pp. 1510-1519.
[16] E. S. Lubana, R. P. Dick, and H. Tanaka, “Beyond BatchNorm: Towards a unified understanding of
normalization in deep learning,” arXiv preprint arXiv:2106.05956, 2021.
[17] Y. Jing et al., “Neural Style Transfer: A Review” in IEEE Transactions on Visualization &amp;</p>
      <p>Computer Graphics, vol. 26, no. 11, pp. 3365-3385, Nov. 2020.
[18] Y. I. Shehu, A. Ruiz-Garcia, V. Palade, A. James, “Sokoto Coventry Fingerprint Dataset,” arXiv
preprint arXiv:1807.10609, 2018.
[19] D. P. Kingma, J. Ba, “Adam: A method for stochastic optimization,” in 3rd International</p>
      <p>Conference for Learning Representations, arXiv preprint arXiv:1412.6980, 2015.
[20] H. Kim, X. Cui, M. -G. Kim and T. H. B. Nguyen, “Fingerprint Generation and Presentation Attack
Detection using Deep Neural Networks,” in Proceedings of 2019 IEEE Conference on Multimedia
Information Processing and Retrieval (MIPR), 2019, pp. 375—378,
https://doi.org/10.1109/MIPR.2019.00074.
[21] Striuk, O.S., Kondratenko, Y.P. (2023). Generative Adversarial Networks in Cybersecurity:
Analysis and Response. In: Kondratenko, Y.P., Kreinovich, V., Pedrycz, W., Chikrii, A.,
GilLafuente, A.M. (eds) Artificial Intelligence in Control and Decision-making Systems. Studies in
Computational Intelligence, vol 1087. Springer, Cham.
https://doi.org/10.1007/978-3-031-257599_18
[22] R. Cappelli, M. Ferrara, and D. Maltoni, “Minutia cylinder-code: A new representation and
matching technique for fingerprint recognition,” IEEE Transactions on Pattern Analysis and
Machine Intelligence, vol. 32, no. 12, pp. 2128-2141, 2010.
[23] C. Sousedik and C. Busch, “Presentation attack detection methods for fingerprint recognition
systems: a survey,” IET Biometrics, vol. 3, no. 4, pp. 219-233, 2014.
[24] A. Roy, N. Memon, J. Togelius and A. Ross, “Evolutionary Methods for Generating Synthetic
MasterPrint Templates: Dictionary Attack in Fingerprint Recognition,” 2018 International
Conference on Biometrics (ICB), Gold Coast, QLD, Australia, 2018, pp. 39-46,
https://doi.org/10.1109/ICB2018.2018.00017.
[25] S. A. Grosz, K. P. Wijewardena, and A. K. Jain, “ViT Unified: Joint Fingerprint Recognition and</p>
      <p>Presentation Attack Detection,” arXiv preprint arXiv:2305.07602, 2023.
[26] S. Purnapatra et al., “Presentation Attack Detection with Advanced CNN Models for
Noncontactbased Fingerprint Systems,” arXiv preprint arXiv:2303.05459, 2023.
[27] A. Rai et al., “An Open Patch Generator based Fingerprint Presentation Attack Detection using</p>
      <p>Generative Adversarial Network,” arXiv preprint arXiv:2306.03577, 2023.
[28] O. Striuk, Y. Kondratenko, I. Sidenko and A. Vorobyova, “Generative Adversarial Neural
Network for Creating Photorealistic Images,” 2020 IEEE 2nd International Conference on Advanced
Trends in Information Theory (ATIT), Kyiv, Ukraine, 2020, pp. 368-371,
https://doi.org/10.1109/ATIT50783.2020.9349326.
[29] O. Striuk and Y. Kondratenko, “Cross-Domain Reconfigurable GAN with Fuzzy Components for
Anomaly Detection,” 2023 13th International Conference on Dependable Systems, Services and
Technologies (DESSERT), Athens, Greece, 2023, pp. 1-5,
https://doi.org/10.1109/DESSERT61349.2023.10416521.
[30] O.S. Striuk, Y.P. Kondratenko, “Generative Adversarial Neural Networks and Deep Learning:
Successful Cases and Advanced Approaches,” International Journal of Computing, vol. 20, issue 3,
pp. 339-349, 2021.
[31] O. Striuk and Y. Kondratenko, “Implementation of Generative Adversarial Networks in Mobile
Applications for Image Data Enhancement,” Journal of Mobile Multimedia, vol. 19, no. 03, pp.
823–838, 2023. https://doi.org/10.13052/jmm1550-4646.1938.
[32] Y. Kondratenko et al., “Analysis of the Priorities and Perspectives in Artificial Intelligence
Implementation,” 2023 13th International Conference on Dependable Systems, Services and
Technologies (DESSERT), Athens, Greece, 2023, pp. 1-8,
https://doi.org/10.1109/DESSERT61349.2023.10416432.
[33] Z. Zhuo et al., “HybridNorm: Towards Stable and Efficient Transformer Training via Hybrid</p>
      <p>Normalization,” arXiv preprint arXiv:2503.04598, 2025.
[34] J. Zhu et al., “Transformers without Normalization,” arXiv preprint arXiv:2503.10622, 2025.
[35] B. Faye, H. Azzag, M. Lebbah, “Cluster-Based Normalization Layer for Neural Networks,” arXiv
preprint arXiv:2403.16798, 2024.
[36] B. Adami, N. Karimian, “GRU-AUNet: A Domain Adaptation Framework for Contactless</p>
      <p>Fingerprint Presentation Attack Detection,” arXiv preprint arXiv:2504.01213, 2025.
[37] B. Adami et al., “A Universal Anti-Spoofing Approach for Contactless Fingerprint Biometric</p>
      <p>Systems,” arXiv preprint arXiv:2310.15044, 2023.
[38] A. Vurity et al., “ColFigPhotoAttnNet: Reliable Finger Photo Presentation Attack Detection</p>
      <p>Leveraging Window-Attention on Color Spaces,” arXiv preprint arXiv:2503.05247, 2025.
[39] M. F. Ramos et al., “Secure Multi-Party Biometric Verification using QKD assisted Quantum</p>
      <p>Oblivious Transfer,” arXiv preprint arXiv:2501.05327, 2025.
[40] E. Kablo et al., “The (Un)suitability of Passwords and Password Managers in Virtual Reality,”
arXiv preprint arXiv:2503.18550, 2025.
[41] S. Cavasin et al., “Fingerprint Membership and Identity Inference Against Generative Adversarial</p>
      <p>Networks,” arXiv preprint arXiv:2406.15253, 2024.
[42] H. Fisher, M. Shahar, Y. S. Resheff, “Neural Fingerprints for Adversarial Attack Detection,” arXiv
preprint arXiv:2411.04533, 2024.
[43] H. Kaur, R. Shukla, I. Echizen, P. Khanna, “Secure and Privacy Preserving Proxy Biometrics
Identities,” arXiv preprint arXiv:2212.10812, 2022.</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          [1]
          <string-name>
            <given-names>A. K.</given-names>
            <surname>Jain</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            <surname>Nandakumar</surname>
          </string-name>
          ,
          <article-title>and</article-title>
          <string-name>
            <given-names>A.</given-names>
            <surname>Ross</surname>
          </string-name>
          , “
          <volume>50</volume>
          years of biometric research: Accomplishments, challenges, and opportunities,”
          <article-title>Pattern Recognition Letters</article-title>
          , vol.
          <volume>79</volume>
          , pp.
          <fpage>80</fpage>
          -
          <lpage>105</lpage>
          ,
          <year>2016</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          [2]
          <string-name>
            <given-names>S.</given-names>
            <surname>Minaee</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Abdolrashidi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>H.</given-names>
            <surname>Su</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Bennamoun</surname>
          </string-name>
          , and
          <string-name>
            <given-names>D.</given-names>
            <surname>Zhang</surname>
          </string-name>
          , “
          <article-title>Biometric Recognition Using Deep Learning: A Survey,”</article-title>
          <source>IEEE Transactions on Pattern Analysis and Machine Intelligence</source>
          , vol.
          <volume>44</volume>
          , no.
          <issue>7</issue>
          , pp.
          <fpage>3543</fpage>
          -
          <lpage>3567</lpage>
          ,
          <year>2022</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          [3]
          <string-name>
            <given-names>I.</given-names>
            <surname>Goodfellow</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J.</given-names>
            <surname>Pouget-Abadie</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Mirza</surname>
          </string-name>
          ,
          <string-name>
            <given-names>B.</given-names>
            <surname>Xu</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Warde-Farley</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Ozair</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Courville</surname>
          </string-name>
          , J. Bengio, “Generative Adversarial Networks,”
          <source>in Proceedings of the International Conference on Neural Information Processing Systems (NIPS)</source>
          <year>2014</year>
          , pp.
          <fpage>2672</fpage>
          -
          <lpage>2680</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [4]
          <string-name>
            <given-names>A.</given-names>
            <surname>Radford</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Metz</surname>
          </string-name>
          , and
          <string-name>
            <given-names>S.</given-names>
            <surname>Chintala</surname>
          </string-name>
          , “
          <article-title>Unsupervised representation learning with deep convolutional generative adversarial networks</article-title>
          ,
          <source>” arXiv preprint arXiv:1511.06434</source>
          ,
          <year>2015</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [5]
          <string-name>
            <given-names>T.</given-names>
            <surname>Karras</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Laine</surname>
          </string-name>
          , and T. Aila, “
          <article-title>A style-based generator architecture for generative adversarial networks</article-title>
          ,
          <source>” in Proceedings of the IEEE conference on computer vision and pattern recognition</source>
          ,
          <year>2019</year>
          , pp.
          <fpage>4401</fpage>
          -
          <lpage>4410</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [6]
          <string-name>
            <given-names>J.</given-names>
            <surname>Zhu</surname>
          </string-name>
          , T. Park,
          <string-name>
            <given-names>P.</given-names>
            <surname>Isola</surname>
          </string-name>
          ,
          <article-title>and</article-title>
          <string-name>
            <given-names>A. A.</given-names>
            <surname>Efros</surname>
          </string-name>
          , “
          <article-title>Unpaired image-to-image translation using cycleconsistent adversarial networks</article-title>
          ,
          <source>” in Proceedings of the IEEE international conference on computer vision</source>
          ,
          <year>2017</year>
          , pp.
          <fpage>2223</fpage>
          -
          <lpage>2232</lpage>
          .
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>