Re: automatic detection out-of-focus images

Posted by Gabriel Landini on Mar 12, 2011; 9:13am
URL: http://imagej.273.s1.nabble.com/JACoP-parameter-and-PSF-tp3685080p3685085.html

On Friday 11 Mar 2011, you wrote:
> Has anyone developed an algorithm in ImageJ for determining if an image
> is out-of-focus?

In addition to the links that Dan provided, be aware that there is no method
to say with certainty if one single arbitrary photo is in focus unless you
know in advance the image contents.
For example, a photo of a field that has no high frequency features might be
impossible to tell apart from another which is out of focus.
That is why most autofocusing methods use a search or scan over the z axis to
find the frame or region that contains the highest contrast or high frequency
components.

In microscopy the problem is worse than standard photography because we deal
with semi transparent objects in different z planes, so one might not be
focusing exactly the same thing at various z distances. In such instances,
defining depth from focus fails (that is there might be highly focused regions
in more than one z plane).

Cheers

Gabriel