Figure 2

Quantitative collagen structural features extracted from automatic image analysis. (A) Representative TPE (red) and SHG (green) images, which specify the collagen structures. The collagen has two distinct models: aggregated thick collagen (ATC) and dispersed thin collagen (DTC). The ATC area contains highly concentrated and aggregated collagen fibers as indicated by the yellow arrow. The collagen in the DTC area is evenly and sparsely distributed as shown by the white arrow. The blue box indicates the area depicted in parts (C–E). (B) Our intensity-morphology based filter is able to differentiate these two types of regions successfully as shown by the yellow and white arrow. (C) The collagen signal is detected using a GMM model, and their connectivity is preserved for a better structural description. (D) Skeletonization was applied to the collagen binary image in order to identify the central line of the fiber network. (E) Similar solutions are applied to the TPE channel, and we extract the features from TPE accordingly. (F) Illustration of collagen fiber length (CFL). (G) Illustration of collagen fiber thickness (CFT). (H) Junction points detection (yellow dots) to measure the collagen network complexity.