Figure 2.

Feature maps for automated detection of superoxide flashes. (A) Averaged cell image showing fluorescent staining of mitochondria. (B) Peak map (ΔF_max) showing maximum increase of fluorescence intensity at each pixel. (C) Histogram of ΔF_max (open circles) and Gaussian fitting of its left portion (solid line), yielding mean (m) and standard deviation (σ). (D) Peak-site map. Binary map after thresholding the peak map at the level of m + kσ; in this case, k = 3. (E) Peak-time map showing the time (0–100 s, color-coded) when local fluorescence increase attained its peak. (F) Combinatorial map derived from D and E, showing tentative flash sites and respective peak times. (G) Overlay of contours of detected flashes on the averaged cell image.