# Save Alignment for Touchscreen Using Calibration API

Elo provides a standard calibration utility for video alignment. The CALIBRATION is used to convert touches from the Elo coordinate system to Windows virtual coordinate system.

The driver uses the following equation to convert a raw touch coordinate point from Elo coordinate system to the Windows screen coordinate system.

Calibration equation is

Xcal = a + m*Xuncal,

where,

Xuncal, is in Elo coordinate system

Xcal, is in Windows coordinate system

m = nScrDx / nEloDx

"a", is the X offset value entry

nScrDx = distance between targets in Windows virtual coordinates

nEloDx = distance between targets in Elo coordinates.

This is specially useful if you want to save the calibration over the network or in some other place, and later configure the touchscreen using one common data set.

To get the current calibration data from driver use EloGetCalibrationData, for changing the data use EloSetCalibrationData

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