Fig. 2.

CF position tracking with the EdgeLength detection system. A: The picture from the camera (top) as displayed by IonWizard software. CF positions are analysed in user-defined windows (red and green boxes) through threshold detection. The black trace underneath the photographic image represents light intensity, summed up over Y for all X positions. The red and green traces show the first derivative, with minima showing bright-to-dark transition (from left) and maxima - dark-to-bright. By defining a threshold (see colour-coded horizontal line cutting across first derivative) one can track the CF edge (here left edge; see arrows. Scale arrows = 25 μm. B) Changes in distance between CF are visualised for further analysis. A mouse cardiomyocyte is shown.