Bio-Rad Quantity One 1-D Analysis Software - Manual (Page 83)

Quantity One User Guide
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Background Slider
To manually adjust the background subtraction levels, drag the Background slider to
the right. You can also move the slider incrementally by clicking on the slider bar, or
type a specific value into the field next to the bar.
Objects with signal intensities lower than the subtraction level will be eliminated
from the image when you click on OK.
Background Box
Use the Background Box function to define a background area in the gel that is
representative of the background in the entire image. This method of subtraction is
useful for images with uniform backgrounds.
Click on the Background Box button, then drag on a background area of the image.
The average intensity of the pixels in the box will be used as the background level to
be subtracted from the entire image.
Background Stripe
The Background Stripe function is useful for gels in which the background changes
from top to bottom (e.g., gradient gels).
Click on the Background Stripe button, then drag on a background region to create a
rectangular box down the length of the image. The average intensity of each
horizontal row of pixels in the stripe will be subtracted from each pixel in that row
across the entire gel. This way, if the image has more background at the bottom than
at the top, more background will be removed from the lower regions of the image.
Note: Make sure that the background stripe runs the entire length of the lanes down the
gel. The average of the topmost row in the stripe will be subtracted from all rows
above the stripe, and the average of the bottommost row will be subtracted from
all rows below.
The minimum and maximum intensities in the stripe are displayed next to the Min
and Max labels in the box. Also, the average intensity value for the entire stripe is
displayed next to Avg.