User`s manual

Chapter 5: Analysis Tools
5-27
Adjusting the Baseline:
As a default, the baseline value is set to Auto Base. As the baseline is adjusted, the
values for all peaks are updated to reflect the new baseline.
All of the following functions are found in the Background Subtraction menu:
Auto Base
This method breaks the red line defining the left boundary of the lane into sixteen
regions, and outputs sixteen points which reflect the average backgrounds across those
sixteen regions. The user can manipulate the 16 points by clicking and dragging. The
user may also designate more points than the 16 and manipulate those in the same
fashion.
Intra-Lane
This method uses the lower of the two values at the edges of the lane along its travel as
the background. If the section of the image is used is wider than the bands, then this is a
very effective way of removing co-migrating material from your measurements. This
method should only be used if the bands are completely enclosed. This is because when
the edges of your lane area intersect any of your bands, band material will be considered
as background, severely affecting your results.
Rubber Band
This method can be thought of as stretching a rubber band underneath the lane profile.
This option does not work well if the values at the ends of the intensity profile are lower
than the rest of the intensity pixels. We do not recommend this method for images with
poorly separated bands.
Minimum Profile
This method takes the lowest value on the profile of each lane as the background for that
lane. We do not recommend this method for lanes where the beginning or end of the lane
is the lowest point as this is dependent on where the lane boundary was placed when it
was defined. This can be hard to repeat between analysis of the same gel.
Valley to Valley