摘要 |
Apparatus for use in a lumen is provided, including a light source, configured to illuminate a vicinity of an object of interest of a wall of the lumen, and an optical system (20), which is configured to generate a plurality of images of the vicinity. The apparatus further includes a control unit, which configured to measure a first brightness of a portion of a first one of the plurality of images generated while the optical system (20) is positioned at a first position with respect to the vicinity, measure a second brightness of a portion of a second one of the plurality of images generated while the optical system (20) is positioned at a second position with respect to the vicinity, the second position different from the first position, wherein the portion of the second one of the images generally corresponds to the portion of the first one of the images, and calculate a distance to the vicinity, responsively to the first and second brightnesses. Other embodiments are also described. |