Analyzing the Structure of Handwritten Digits: A Comparative Study of PCA, Factor Analysis, and UMAP

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1. Verfasser: Gupta, Jyotiraditya
Format: Preprint
Veröffentlicht: 2026
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author Gupta, Jyotiraditya
author_facet Gupta, Jyotiraditya
contents Handwritten digit images lie in a high-dimensional pixel space but exhibit strong geometric and statistical structure. This paper investigates the latent organization of handwritten digits in the MNIST dataset using three complementary dimensionality reduction techniques: Principal Component Analysis (PCA), Factor Analysis (FA), and Uniform Manifold Approximation and Projection (UMAP). Rather than focusing on classification accuracy, we study how each method characterizes intrinsic dimensionality, shared variation, and nonlinear geometry. PCA reveals dominant global variance directions and enables high-fidelity reconstructions using a small number of components. FA decomposes digits into interpretable latent handwriting primitives corresponding to strokes, loops, and symmetry. UMAP uncovers nonlinear manifolds that reflect smooth stylistic transitions between digit classes. Together, these results demonstrate that handwritten digits occupy a structured low-dimensional manifold and that different statistical frameworks expose complementary aspects of this structure.
format Preprint
id arxiv_https___arxiv_org_abs_2601_06168
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Analyzing the Structure of Handwritten Digits: A Comparative Study of PCA, Factor Analysis, and UMAP
Gupta, Jyotiraditya
Computer Vision and Pattern Recognition
Handwritten digit images lie in a high-dimensional pixel space but exhibit strong geometric and statistical structure. This paper investigates the latent organization of handwritten digits in the MNIST dataset using three complementary dimensionality reduction techniques: Principal Component Analysis (PCA), Factor Analysis (FA), and Uniform Manifold Approximation and Projection (UMAP). Rather than focusing on classification accuracy, we study how each method characterizes intrinsic dimensionality, shared variation, and nonlinear geometry. PCA reveals dominant global variance directions and enables high-fidelity reconstructions using a small number of components. FA decomposes digits into interpretable latent handwriting primitives corresponding to strokes, loops, and symmetry. UMAP uncovers nonlinear manifolds that reflect smooth stylistic transitions between digit classes. Together, these results demonstrate that handwritten digits occupy a structured low-dimensional manifold and that different statistical frameworks expose complementary aspects of this structure.
title Analyzing the Structure of Handwritten Digits: A Comparative Study of PCA, Factor Analysis, and UMAP
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2601.06168