One or more techniques and/or systems for detecting edges in images of objects subjected to imaging using imaging apparatus are disclosed, such that the effect of image noise on the edge detection can be mitigated. Ratios of intensity values (e.g., signal values) for a subject region (e.g., a pixel) and respective adjacent regions are determined. An adaptive threshold value is determined for respective adjacent region pairs. The ratio value is compared to the adaptive threshold value for respective adjacent region pairs, to determine whether an edge is present between the respective adjacent region pairs.