Calibrate

Measurements are displayed with length in pixels until you have calibrated the image. Calibration should be perfomed by using an object of known size in the same plane as what is of interest (f.e. a coronary artery).
Start the caibration tool via the menu of the image window, 'Tools' and select 'Calibrate'. With the left mouse button you can now make a calibration measurement, same as you do with the measuring tool; the right mouse button enables you to zoom and use the panning window to pan the zoomed image. The calibration mode can be cancelled by pressing the escape button or by taking a measurement of 0 length. The text in the window shows you the calibration mode is active.
Zoom the image to calibrate more accurately. See image below.



After you have taken the calibration measurement, you'll be presented with the calibration window, enabling you to make up to 3 calibration choices: Press 'OK' to use the distance you chose or press 'Cancel' to cancel the calibration. See image below.


Further items you need to know:
-There are 2 indications that measurements are calibrated: 1)length in pixels and 2)text in the bottom left of the image window
-Biplane images need to be calibrated individually
-The calibration measurement always remains visible and can only be deleted by making a new calibration and entering the value of 0.0
-In case of f.e. x-ray, due to the diverging x-ray beam, object of the same size but placed at different distances from the source of the beam, appear to have different sizes
-An image pixel is assumed to be square