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XY Drift

Due to temperature differences, thermal lateral drift can occur between two successive images while scanning. Using XY Drift analysis can calculate the lateral shift between two images. You can also manually enter the drift.

Requirements

Two images captured sequentially with the same scan direction are required. The capture and trace directions must be the same for both images (up/down, trace/retrace), and the images must have the same microscope configuration and scanner calibration properties.

XY Drift Procedure

To calculate XY Drift using NanoScope software:

 
  1. Identify the two images to be compared with XY Drift analysis, and open the first (chronologically) of the two images. Use one of the following methods to open the XY Drift analysis view:
  1. You can open the XY Drift view, shown in Figure 2, using one of the following methods: 
  • Right-click on the image name in the Workspace and select Add View > XY Drift from the popup menu. See Figure 1.

Figure 1: Select XY Drift from the workspace

 

Or

  • Right-click on a thumbnail in the Multiple Channel window and select XY Drift.

Or

Select Analysis > XY Drift from the menu bar.

Or
  1. Click the XY Drift icon in the NanoScope toolbar.
 
  1. The XY Drift view, shown in Figure 2, appears showing the selected image.

Figure 2: XY Drift Interface

 
  1. Use the Load Image button to browse for the subsequent image.
  2. Click the Calculate Shift button. The software will calculate the shift of the second image relative to the first image.
  3. The results display in the Results panel.
  1. To apply the corrections in the Inputs box, click the Apply Correction button.
  2. Or
  3. You can also manually enter the correction values in the Inputs box. Click the Apply Correction button.
NOTE: Apply Correction affects RealTime by applying a drift correction to the RealTime images. Do not use Apply Correction if this is not your intent.
NOTE: XY drift corrections calculated from other than the two most recently captured images may not reflect current environmental conditions.

XY Drift Parameters

Statistics used by the XY Drift analysis are defined in this section.

Parameter Description

Number of scan lines

Specifies the number of lines to calculate.

Flatten

Flattens both images before the shift is calculated. (Use the Undo Flattenbutton to reverse the flatten).

X Correction

Specifies the amount of correction to apply to the X-axis of the scanner.

Y Correction

Specifies the amount of correction to apply to the Y-axis of the scanner.

Second Image

Defines the location of the second image used in the analysis.

Image resize factor

Speeds up the shift calculation by averaging for images larger than 512 pixels

Orientation

Settings:

Order of operation

  • Left to right: Left image (1st) to right image (2nd).
  • Right to left: Right image (2nd) to left image (1st).
  • Best of both: performs both Left to right and Right to left calculations and averages them.

Table 1: XY Drift Parameters

Results of the XY Drift analysis are presented in this section.

Parameter Description

X Shift

Specifies the amount of calculated shift along the X-axis of the second image relative to the first.

Y Shift

Specifies the amount of calculated shift along the Y-axis of the second image relative to the first.

Tested Correlation Coefficient

Reports the correlation coefficient after correcting for the detected shift. A perfect correlation is 1.0. If the tested correlation coefficient is too low, then the calculation is not valid and should not be applied. You may need features that have more distinct contrast.

Raw Correlation Coefficient

Reports the correlation coefficient between the two images prior to processing.

Table 2: Results Parameters

Parameter Description

Load Image

Browse to open the second image in the right box.

Calculate Shift

Compares left image to right image, and reports the shift statistics in the Results box.

Apply Correction

Applies the correction in the Inputs box to the second image.

Undo Flatten

Undo Flatten restores the image to its original form.

Table 3: XY Drift Buttons

 

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