Systems and methods for determining distance from an object

Abstract

A process is provided for conducting an eye examination using a mobile device, the process comprising capturing a first image of an object using a camera of a mobile device set to a fixed focusing distance; determining, with reference to the first image, an absolute size of the object; capturing a second image of the object using the camera of the mobile device; determining, with reference to the second image, a distance from the mobile device to the object; providing an indication via the mobile device to move the mobile device relative to the object; and receiving input from the mobile device in response to the eye examination program.

What is claimed is: 
     
         1 . A process for conducting an eye examination using a mobile device, the process comprising:
 capturing a first image of an object using a camera of a mobile device set to a fixed focusing distance;   determining, with reference to the first image, an absolute size of the object;   capturing a second image of the object using the camera of the mobile device;   determining, with reference to the second image, a distance from the mobile device to the object;   providing an indication via the mobile device to move the mobile device relative to the object; and   receiving input from the mobile device in response to the eye examination program.   
     
     
         2 . The method of  claim 1 , wherein the object is an optotype displayed in connection with the eye examination program. 
     
     
         3 . The method of  claim 1 , wherein the object is a test pattern. 
     
     
         4 . The method of  claim 1 , wherein determining, with reference to the first image, an absolute size of the object further comprises determining a first image size of the object in the first image. 
     
     
         5 . The method of  claim 4 , wherein determining, with reference to the first image, an absolute size of the object is performed with reference to the first image size of the object in the first image, a focal length of the camera of the mobile device, a second distance between the lens and the focal plane of the camera, and a third distance from the lens at which the object is in optimal focus. 
     
     
         6 . The method of  claim 1 , wherein determining, with reference to the second image, a distance from the mobile device to the object further comprises determining a second image size of the object in the second image. 
     
     
         7 . The method of  claim 6 , wherein determining, with reference to the second image, a distance from the mobile device to the object is performed with reference to the second image size of the object in the second image, the absolute size of the object, and the focal length of the camera of the mobile device. 
     
     
         8 . The method of  claim 1 , wherein providing an indication via the mobile device to move the mobile device relative to the object comprises providing an indication via the mobile device to move the mobile device in a direction relative to the object. 
     
     
         9 . The method of  claim 1 , wherein providing an indication via the mobile device to move the mobile device relative to the object comprises providing an indication via the mobile device to move the mobile device to a second distance from the object. 
     
     
         10 . The method of  claim 9 , wherein the second distance corresponds to an optimal distance for conducting an eye examination test. 
     
     
         11 . A mobile device comprising:
 a camera;   a visual display; and   a processor coupled to the camera, the processor configured to:
 capture a first image of an object using the digital camera; 
 determine, with reference to the first image, an absolute size of the object; 
 capture a second image of the object using the digital camera; 
 determine, with reference to the second image, a distance from the mobile device to the object; 
 provide an indication via the display to move the mobile device relative to the object; and 
 receive input from the mobile device in response to an eye examination program. 
   
     
     
         12 . The mobile device of  claim 11 , wherein determining, with reference to the first image, an absolute size of the object further comprises determining a first image size of the object in the first image. 
     
     
         13 . The mobile device of  claim 12 , the camera comprising a lens having a focal length and a focal plane, wherein determining, with reference to the first image, an absolute size of the object is performed with reference to the first image size of the object in the first image, the focal length, a second distance between the lens and the focal plane, and a third distance from the lens at which the object is in optimal focus. 
     
     
         14 . The mobile device of  claim 11 , wherein determining, with reference to the second image, a distance from the mobile device to the object further comprises determining a second image size of the object in the second image. 
     
     
         15 . The mobile device of  claim 14 , the camera comprising a lens having a focal length, wherein determining, with reference to the second image, a distance from the mobile device to the object is performed with reference to the second image size of the object in the second image, the absolute size of the object, and the focal length. 
     
     
         16 . The mobile device of  claim 11 , wherein providing an indication via the display to move the mobile device relative to the object comprises providing an indication via the display to move the mobile device in a direction relative to the object. 
     
     
         17 . The mobile device of  claim 11 , wherein providing an indication via the display to move the mobile device relative to the object comprises providing an indication via the display to move the mobile device to a second distance from the object. 
     
     
         18 . The method of  claim 17 , wherein the second distance corresponds to an optimal distance for conducting an eye examination test.