Average brightness values for PCH measurements are shown in Figure 3C.
Each function has a peak center, ⟨ Z⟩, and width, σ, related to the mean fluorophore brightness values ⟨ Ired⟩f and ⟨ Iblue⟩f according to eqs 2 and 3.
Contrasts between the white badge and the background or body were measured as the differences between the values of mean brightness recorded for each square.
After standardization of the EUS images, brightness values including the mean (Tmean), indicative of echogenicity, and the standard deviation (TSD), indicative of heterogeneity, in the tumors were analyzed.
We calculated the root-mean-square (RMS) contrast for every image within this analysis window, i.e. the standard deviation of the brightness values of each pixel from the mean brightness, divided by the mean brightness (van der Schaaf and van Hateren, 1996; Brinkworth and O'Carroll, 2009).
The mean brightness of each ROI is determined using numerical values assigned to grey-scale pixels.
The simple method to find out the separated point is to test all possible gray-scale values from 0 to L−1 of the histogram by calculating the difference between the mean brightness of input and the mean brightness of output.
Calculate the mean brightness within the region.
Mean brightness is an indicator of the illumination level.
