Bio-Rad EXQuest Spot Cutter - Manual (Page 66)

EXCISION TOOL CONTROLS
8-2
8.3 TRANSFORM DIALOG BOX
The "Transform" dialog box is used to adjust the image brightness and contrast. It contains controls used to
view the pixel intensity frequency distribution; manually or automatically transform the image; check for
saturated pixels; or color the image.
Figure 8-3. “Transform” Dialog
Transform Controls
• Full scale/Low-High: Select the Full scale option to display the full frequency distribution or the
Low-High option to magnify the frequency distribution between the High and Low sliders.
• Log: Check the Log checkbox to change the way data are displayed in the histogram. This function
is used to better discern subtle changes in signal intensity.
• High/Low sliders. Use the High and Low sliders to optimize the preview image manually. Drag the
High slider handle to the left to make weak signals appear darker. Drag the Low slider handle to the
right to reduce preview image background. As you drag the sliders, examine the Frequency
Distribution Histogram. Everything to the left of the Low slider will be remapped to minimum
intensity, while everything to the right of the High slider will be remapped to maximum intensity.
Position the markers at the ends of the data range in the histogram, and use the low slider to cut off
the "spike" of background noise. You can also type specific high and low values in the fields to the
right of each slider. Click anywhere on the slider bars to move them incrementally. If the image data
are in a narrow range, select the Log High/Low Sliders check box. This allows finer adjustments
with the slider handles.
• Gamma Slider. Some images may be more effectively visualized if their data are mapped to the
computer screen in a nonlinear fashion. Adjust the Gamma slider handle to expand or compress the
contrast range at the dark or light end of the range, and to reflect this in the transform plot and
preview window. You can also type a specific value in the field to the right of the slider.
• Calibrated Quantity: When images have been acquired with a densitometer, click Calibrated
Quantity to display the image units in O.D.s.
Frequency Distribution
Histogram
Transform Plot
Preview Window