Comet Labs WN591 Manual de usuario descargar pdf (Pagina 21)

Help! There is a comet in my computer! 18

3.5.4 Comet profile

We have now done all the necessary things to tackle a new task – the comet profile of

light intensities. An example of a comet profile is shown in Figure 9. How does the

computer calculate and draw the profile?

Figure 9. The comet profile for a comet recorded from a microscope slide.

The comet profile is a graph showing the total intensities of pixel columns along the x-

axis of the comet. So all we need to do to get a comet profile for our model image is to

plot a graph from the data in Table 1 (column Background-corrected comet intensity),

taking into account the background signal (Figure 10A). The same principles can also be

applied to close-fitting segmentation (Figure 10B).

For accurate measurement, the background profile should have similar values along the

x-axis (Figures 9, 10). Any “bumps” in the background profile indicate that there is a

part of a comet or some other fluorescing object included in the background ROI. In such

cases, we need to re-position the background box or cancel measurement of this particular

comet. A gradual upwards or downwards slope in the background profile indicates that a

part of a comet is most likely included in the background ROI. If all comets recorded at the

same position on the image have a sloping background profile, the problem is probably

severe shading of the image (see chapter Shading, page 35). Comets with sloping

backgrounds should not be measured.

Recorded comet intensity

Background-corrected comet intensity

Scaled background intensity

Recorded comet intensity

Background-corrected comet intensity

Scaled background intensity

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Comet Labs WN591 Manual de usuario Pagina 21