Bright light and light diffusion

Discussion in 'Optometry Archives' started by Pauli Soininen, Jul 17, 2005.

  1. Human vision is usually at its best when looking in bright daylight due to
    the great amount of light and small pupil size, which means less corneal
    aberration (and also good depth of field). However, highly bright objects
    like the sun (or a reflection of the sun on a car for example) get a large
    glare and diffusion around them.

    What is the exact explanation: Why do the image areas with lower light level
    not appear diffused at all, while bright objects are totally diffused? Note
    that I'm not talking about the starburst effect caused by squinting the eye
    (where the tear film has very elevated edges). So the eyes are kept wide

    As it is explained in the above links (in Response Compression and
    Luminosity Discrimination parts), image areas with high brightness will seem
    somewhat equally bright even if they have slight brightness variation, in
    other words, very big brightness difference is needed for the difference to
    be detected when high brightness is in case.

    Is this the explanation to my question or is there something else?

    Is it correct to say, that if one sees halos and starburst around bright
    objects, the same halo and starburst pattern are there around all objects
    (except black objects) but they are just not detected around dim objects due
    to this Weber-Fechner law?

    ps. A similar thing of course happens with camera optics, where in the
    result image the sun is highly diffused while the rest of the picture is
    flawless (the amount of main starburst rays is defined by the polygon
    aperture and the rest of the diffusion is caused by the reflections between
    each optical element and other miscellaneous aberration).
    Pauli Soininen, Jul 17, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.