1. Background

MNIST Dataset

Classification vs Regression

Classification Regression
Output target variables are discrete Continuous numerical value
Goal Predict category Predict exact numerical value
Evaluation Precision, Recall, F1-Score MSE, R2-Score, MAPE, RMSE
Decision boundary Clearly defined between different classed No distinct boundaries
Algorithm Logistic regression, Decision trees, Support Vector Machines (SVM) Linear Regression, Polynomial Regression, Decision Trees (with regression objective).

Why regression?

MNIST는 일반적으로 classification 문제로 접근하지만, 본 실험에서는 regression 방식으로도 충분히 높은 성능을 낼 수 있는지 검증해보고자 하였음.

Regression은 label 간 거리 정보를 활용할 수 있어 더욱 정교한 loss 계산이 가능할 것

2. Image Regression Methods

Image = matrix of numbers

ways to handle 2d structure:

Method1 - MLP 방식

Multilayer Perceptron: Fully Connected Layer로만 구성됨

Method2 - CNN 방식

기존 CNN의 Feature Extraction + Regression

Structure explanation - different input to flatten