Measuring in Photos: Import and Recalibrate

OsiriX and Horos Course · Measurements and Tools

In this lesson I show how to take measurements on photos (JPEG/BMP, etc.) inside OsiriX and how to recalibrate the scale so that measurements stop appearing in pixels and start appearing in centimeters — letting you measure distances, dimensions and even area (cm²). 1) Enable image import (not just DICOM) By default, OsiriX is configured to import DICOM only. To import photos: Go to Preferences Open the Database section Uncheck the “Import DICOM File Format Only” option OsiriX will then also accept image files. 2) Import the photo into the database Go to File → Import Files Select the photo and import it In the video example, I import two photos and open the one that contains a ruler/scale. 3) Why it shows “pixels” and how to fix it If you use the ruler on a photo with no DICOM scale, OsiriX shows the measurement in pixels (the “dots” of the image). That doesn’t help when you need, for example, to calculate: size in centimeters dimensions of a lesion area in cm² 4) Recalibrate: teach OsiriX what 1 cm is The process is: Select the straight ruler Measure a known segment (in the video, 1 cm on the ruler printed in the photo itself) In the example, OsiriX shows that 141 pixels = 1 cm Double-click the measurement and choose Recalibrate Set Distance in centimeters = 1 (equivalent to 10 mm) From that moment on, all rulers return measurements in cm, not in pixels. 5) Measure distance and dimensions After recalibrating: the ruler now shows measurements such as 13 cm you can measure a lesion/ulcer as 2 cm x 1.5 cm, for example 6) Measure area with the brush (cm²) To calculate the area: Select the brush tool Adjust the thickness (in the video, I increase it to 20) “Paint” the ulcer/lesion OsiriX returns the exact area in cm² (in the example: 3.8 cm²) 7) When this is useful This recalibration can be applied to any imported image (JPEG, BMP, etc.), especially when a lab delivers non-DICOM images. You can use a known reference to calibrate: a ruler in the photo itself a body measurement (e.g., “nipple to nipple”) a measurement you take on the patient and enter into OsiriX