One surfactant protein D image, lots of peak number – measurements using various signal processing algorithms.
Just the beginning of the assessment of which peak-finding programs work well with AFM images, are easy to use, and generate more insight than just the opinions of the observers.
There really isnt much new by using these signal processing programs for reasons which I think might be related to the fact that “noise” is a big issue for signal processing, and symmetry and variation are not that well handled. Just a microscopist’s opinion here, not one of a programmer.
Clearly there is still a judgement call to be made on whether to use the “mode or the mean” in deciding what is the best number of peaks. Differences between the number of peaks on the right and left sides of a dodecamer (differences in the way the molecule has fallen on the mica, other processing issues) are clearly a stumbling block to a determination of symmetry in peaks, and the slope, threshold and a number of other signal processing options allow for great variability in peak numbers. I am certainly leaning toward the simplest comparison, that of the human eye, and then a plot with modest peak processing to identify peaks and valleys.
To view the actual image (sadly called 41 aka 45) just roam back through the SP-D posts, it appears a jillion times.