Analysis of Magnification in Depth from Defocus

TL;DR

This paper investigates how magnification affects depth from defocus accuracy, analyzing the impact of scale factors, interpolation errors, and estimator bias in image warping methods.

Contribution

It provides a detailed analysis of magnification effects on DFD accuracy and evaluates the bias and efficiency of scale estimators without explicit scale consideration.

Findings

Magnification significantly influences blur estimation accuracy.

Ignoring scale factors introduces bias in depth estimation.

Interpolation errors affect the precision of warping-based magnification correction.

Abstract

In depth from defocus (DFD), when images are captured with different camera parameters, a relative magnification is induced between them. Image warping is a simpler solution to account for magnification than seemingly more accurate optical approaches. This work is an investigation into the effects of magnification on the accuracy of DFD. We comment on issues regarding scaling effect on relative blur computation. We statistically analyze accountability of scale factor, commenting on the bias and efficiency of the estimator that does not consider scale. We also discuss the effect of interpolation errors on blur estimation in a warping based solution to handle magnification and carry out experimental analysis to comment on the blur estimation accuracy.