Contrast-sensitivity-based evaluation method of a surveillance camera's visual resolution: Improvement from the conventional slanted-edge spatial frequency response method

Zong Qin, Po Jung Wong, Wei Chung Chao, Fang Cheng Lin, Yi-Pai Huang, Han Ping D. Shieh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Visual resolution is an important specification of a surveillance camera, and it is usually quantified by linewidths per picture height (LW/PH). The conventional evaluation method adopts the slanted-edge spatial frequency response (e-SFR) and uses a fixed decision contrast ratio to determine LW/PH. However, this method brings about a considerable error with respect to subjectively judged results because the perceptibility of the human vision system (HVS) varies with spatial frequency. Therefore, in this paper, a systematic calculation method, which combines the contrast sensitivity function characterizing the HVS and e-SFR, is proposed to solve LW/PH. Eight 720P camera modules in day mode, four 720P modules in night mode, and two 1080P modules in day mode are actually adopted. Corresponding to the three modes, mean absolute error between objective and subjective LW/PH are suppressed to as low as 26 (3.6% of 720P), 27 (3.8% of 720P), and 49 (4.5% of 1080P), while those of the conventional method are 68 (9.4% of 720P), 95 (13.2% of 720P), and 118 (10.9% of 1080P).

Original languageEnglish
Pages (from-to)1464-1471
Number of pages8
JournalApplied Optics
Volume56
Issue number5
DOIs
StatePublished - 10 Feb 2017

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