Evaluation of global thresholding techniques in non-contextual edge detection

Abstract

The performance of global thresholding techniques in edge detection is a problem that has yet to be studied in depth. Basically, an edge detection process consists of applying an edge intensity detector sequence and a thresholding technique to a given image. In this paper, we demonstrate that applying this sequence to an image and comparing it with a reference image does not constitute a valid process for the evaluation of global thresholding techniques in edge detection. Instead we propose a method that allows the performance of a global thresholding technique to be jointly or independently evaluated using a detector. Our methodology is applied to assess the performance of seven global thresholding techniques, which have been widely cited in the literature and evaluated in other contexts, using five color image edge intensity detectors. We show how the results may differ depending on the criterion selected. A new criterion is proposed that brings together different aspects, permitting a more valid evaluation of the performance of thresholding techniques both alone or in conjunction with a determined detector.